Chronometer Seamasters

Seamaster chronometers are an odd bunch. Chronometer certification was mostly reserved for the Constellation line-up, and by default, any Chronometer Seamaster is going to be more rare than a Constellation. In addition, they are also less expensive than Constellations making them attractive for entry-level collector. Chronometer Seamasters come in three movement categories distinguished by their movements: 564, 752, 551 and 352.

167.070551Rare, Factory redial
2577352Rare, Bumper
Chronometer Seamaster References and Movements

Of these, the cal 551 can be considered an edge case, because it is actually an Omega Geneve that has had dial changed by the factory. It has been listed here, because some completionist collectors may want to add it to their collection. This blog post focuses less on the day/date versions, because my personal interest resides in the date versions.

Omega Seamaster 168.024

This is probably the most popular of the chronometer seamasters due to the classic oyster-style case familiar from 14700 and 14744. They are characterised by a massive case with beefy lugs and they came with a beads of rice bracelet, a must have for an Omega dress watch enthusiast. It is possible to find these watches with and without cyclops on authentic Omega crystal. Apparently, cyclops was an option you could choose when buying the watch at the time.

The caliber 565 non-chronometer reference 166.010 shares the same case. In the end, there isn’t that much difference. While there is not certainty whether the chronometer version ever shipped with black dial, it is possible that there have been crosshair dial versions both with crosshair piercing the text and crosshair not piercing the text. I haven’t personally handled these watches or seen authoritative take on their existence. I treat all black dial Seamasters without visible radium / tritium plots as redials.

Omega Seamaster ‘Sparkle’ 168.022

The 168.022 comes in a large 36,5mm case and has a nice radial finish. It comes in a few dial variations, with most notable being the ‘Sparkle’ dial. 168.022 features a cal 564 movement and wears well.

The 168.022 have few different variants. Among these, there are a champagne dial and a white dial sparkle. The watches can have T SWISS T dials to indicate presence of tritium plots, but they can also be without tritium plots. Redials are easy to spot, because the dials are hard to reproduce. One should watch out for overly polished cases and cases where the radial finish of the bezel is gone. I haven’t personally seen a legit black dial version yet. They may exist, but July/2021 I assume they don’t.

Omega Seamaster 168.035

These watches are for the quirky 70s cushion case lovers. They are slightly bigger and wear a lot differently from the 36,5mm case Seamasters. The watches measure at 38mm diameter, but they wear a lot smaller due to the short lugs. In addition, the lug width is 22mm and the bracelets are nearly impossible (read expensive) to find loose. It is possible that there have been black dial version of these, but as of now (9/11/2021) this is unclear.

Suspicious black dial variant of the non-chronometer version 166.065. I was initially fooled by the tritium plots, but it may be that the dial is not original.


The 168.022 and 168.024 share the same case with Seamaster 60 ‘Big Crown’ ref 166.062 and various De Ville Chronographs (145.018, 145.017 and 146.017 among others). In addition the bracelets go to the Seamaster 120 case 135.027 / 136.027. Unsurprisingly, because the 1069/524 goes many, much more valuable watches, it is highly sought after by collectors and thus getting scarce and valuable. Interesting history behind 1069/524 is that there are also unbranded ones manufactured by JB Champion which can be used to provide extension links.

It is common to find collectors with 100s of bracelets that they have detached from watch heads and hoarded overtime. One can only speculate the reasons, but one of them is that selling a bracelet and watchhead separately will typically yield more money. As the result, it is not that common to find a chronometer Seamaster on its original bracelet as somebody has collected it into their dragons hoarde of vintage omega parts or mounted it on a more expensive watch.

Bracelet/EndlinksReferencesLug Width
1069/524168.022, 168.02319mm
1098/540168.022, 168.02319mm
1125/560168.022, 168.02319mm
1170/604168.035, 168.03422mm
Chronometer Seamaster Bracelets

Omega cal. 564 Movement

Cal 564 movement is beautifully crafted. The movement should be easy to wind and setting time should be smooth. Only thing to watch out for is a broken quickset date. The parts are not available outside of Omega and they are quite expensive. If one finds a watch with broken quickset date I’d consider not repairing it. In my eyes, broken quickset date doesn’t lower the value of the watch considering how easily they break.

The cal 564 movements are true workhorses. If the movement is not broken, they will wind and run despite years of neglect. For wear, service is recommended.

Türler Dials

Aside from the 2577, all of the watches can be relatively commonly found with Türler print. This is also a common thing that dodgy entry-level Rolex investors add later on, sometimes with a Sharpie and often completely ruining the dial.

Meister Dials

Based on my experience, Meister dials are applied in similar fashion as Türler, but less common (in my experience) than Türler dials. All the same, they can be found. Another favorite thing to add when preparing to make maximum profit.


The chronometer Seamasters are a nice category of vintage Omega watches from collector’s perspective. There are enough references and variants to offer plenty of challenge. Their overall collectibility is still quite low, which makes their prices still quite affordable aside from the elusive bumper chronometer. They are also common enough that there is a market and not all of them are yet in watch collectors dragons hoardes. In addition they are great watches to wear with eloquent dressy designs that stand time.

Omega Aqua Terra Railmaster 2504.52

Movement2402 (ETA 2892-A2)
Lug to lug44mm
Lug width19mm
MaterialStainless Steel
Water Resistance150m
Basic information

Omega Aqua Terra Railmaster is one of the first Omega Railmaster reissues from the early 00s. The watch features no-date 2403 movement and 3-6-9 dial present in the earlier references. The thing to note is that the Aqua Terra Railmaster is not an antimagnetic watch in the spirit of Eberhard Scientigraph, Rolex Milgaus, IWC Ingeniur or the original Omega Railmaster. Instead, as part of the Aqua Terra lineup, the 2504.52 Railmaster was perhaps meant to compete with Rolex Explorer.

The Aqua Terra Railmasters are defined by no date 3-6-9 dial, painted super luminova plots, screwdown crown and co-axial movement. The watches offer 150m water resistance making them durable companions to office dwellers, commuters and downtown mall spelunkers .


The 36mm Aqua Terra Railmaster was released during time when Omega lineup was based on the more is more principle. Similarly to the Planet Oceans, the Aqua Terra Railmaster was released in multiple configurations from 36mm to 49mm. Of these, the 39mm variant is the most popular and easily found. There has been discussion that the 41mm would be the rarest, but they seem to be available at any given moment unlike the 2504.52 or 2804.52 which show up few times a year.

ReferenceSizeLug widthDetails
2504.5236mm19mm1575/899 bracelet
2804.5236mm19mmLeather strap
2503.5239mm20mm1574/898 bracelet
2803.5239mm20mmLeather strap
2103.5239mm20mmYellow gold, yellow gold bracelet
2603.52.3739mm20mmYellow gold, brown leather strap
2603.52.3139mm20mmYellow gold, black leather strap
2502.5241mm21mm1573/887 bracelet
2802.5241mm21mmLeather strap
2806.52.3749mm24mmLeather strap, Manual wound gold, leather strap, manual wound gold, leather strap, manual wound
Aqua Terra Railmaster Chronometer references

If you’re “A Big Watch Guy” the 49mm Railmaster could be a good alternative IWC Pilot a good alternative. In a way, the most interesting reference is the 18k 2103.52 with the 18k gold bracelet. I don’t fancy owning one, but it’d be amazing to see one in person one day.


The bracelet features integrated clasp without any micro adjustments. The bracelet is a typical pin & collar bracelet of the era. The bracelet is robust and serviceable as pins take most of the wear and they can be replaced during the service. The downside is that for amateurs the bracelets can be difficult to adjust and it is easy to bend pins and lose collars.

Bracelet / EndlinkLug WidthBuckle
1575/899 19mm16mm
1574/898 20mm17mm
1573/887 21mm18mm (?)
Aqua Terra Railmaster Chronometer bracelets

For those who suffer from swelling, the bracelet may not be optimal as there is no micro-adjustment. Another issue is getting it properly fit as the size is controlled with half-links. As for the 2504.52, the 19mm to 16mm taper is proportioned and relatively standard and the bracelet is very comfortable.

For perfectionists and people who suffer from OCD, the bracelet design makes it nearly impossible to center the hidden clasp. This may be a serious downside depending on the mental condition of the watch enthusiast.


Field watches and nato straps go together like salt and pepper. The 2504.52 is no exception. For people who can’t live with a cheeky springbar, the 19mm lug width may be difficult to digest. However, if you take the peeking spring bar as a stylistic element, the Railmaster Chronometer can be worn with just about any 18mm Nato.

Another option is leather. I have yet to purchase a 16mm Omega Deployant clasp, but I’m planning to do so and get a quality leather, sailcloth and canvas for change.

Dial and Hands

The 3-6-9 dial is a throwback to the original Railmaster from 1950s. Aside from green super luminova, the Railmaster Chronometer has more text on the dial. The defining feature of the no-date dial is symmetry and simplicity. The dial of the 2504.52 is about the same size as 2201.50. This makes it a very good companion to the 42mm Planet Ocean of the same time. The 2503.52 has a slightly larger dial than 2201.50, which may look out of place next to such imposing dive watch.

With the hands, there comes a major difference to the original railmaster. The original Railmaster has Ranchero style hands with Arrow hour-hand whereas the Aqua Terra Railmaster has a regular hour hand and arrow minute hand. This difference is inherited from the Aqua Terra line-up, which still uses this configuration even today.


The watch is powered by the 2403 movement, which is a no date version of the cal 2500. Just like the cal 2500, due to the early issues with the co-axial escapement, the movement received an upgrade with lower beat rate. It is not a big surprise to anyone that the movement feels and winds exactly like its date sibling, the cal 2500, but without the date adjustment. Crown action is robust and very tool-watchey. The see-through case back is a nice touch and the rhodium plated movement is beautiful.

The 2504.52 is a late addition to the family. The 39mm and the 41mm versions can be found with both movement types 2403A and 2403B. However, all of the examples of the 2504.52 that I have tried to buy have been with 2403B movement with 84xxxx serial. If somebody knows whether the 36mm Railmaster came with a 2403A, I’d be interested to know and update this post.

2504.52 Seen in Wild

ReferenceSerialMovementSoldSeen onPrice
2504.5281699609??2007.1.4Yahoo Auctions Japan 17/10/2021220 000 JPY
2504.52?????Chrono24, Czech Republic4300 EUR
2504.5284699791??October 26th, 2010Chrono24, USA 24/7/20214999 USD
2504.52?????Chrono24, Singapore 11/8/20213755 USD
2504.52846979532403B2012Chrono24, Usa 6/8/20214513€
2504.5284643XXX (mine)2403BYahoo Auctions Japan 25/7/2021300000 JPY
2504.52UnknownUnknownChrono24 (Japan) 2735€
2504.528478XXXX2403BWatchuseek 30/10/20204250 USD
2504.5281699XXX2403BOmegaforums 30/8/20204150 USD
Known 2504.52 serials


The 36mm Railmaster Chronometer is an interesting watch:

  • It can be used to make a poor man’s late 00s trilogy.
  • It is an obscure alternative to Rolex Explorer.
  • It is rare and worth collecting / hunting.

Personally, I find the early co-axial movements interesting and the looks of 2504.52 appealing. It makes an excellent everyday watch and a perfect companion to the 2201.50, which I also like.

In case of errors, please reach me out with DMs. I’d like to correct them.

Rolex GMT Master 16700 & 16710 cheat sheet

Basic Information

NameRolex GMT MasterRolex GMT Master II
Lug to lug47,5mm47,5
Lug width20mm20mm
Water Resistance100m100m
Basic information

The two watches are very similar, but they have a few key differences. The movement of 16710 is more advanced and allows user to move hour & GMT hand independently. The 16700 works like any other watch, except GMT hand completes a single revolution in 24h timespan.

In addition to the functional differences due to the movement, there are other differences. 16700 was never offered with a SEL bracelet, and its manufacturing stopped at 2000 and 16710 came with two movements.


BezelOnly Pepsi / BlackBlack, Pepsi and Coke
TritiumBefore 1998Before 1998
Swiss only/Luminova1998-19991998-1999
Super luminovaNeverAfter 1999
Lug holes AlwaysBefore 2000
Solid end-link braceletNeverAfter 2000
Cal 3186 movementNeverVery late in production
Rolex GMT Master 16700 with SEL bracelet.

Personal Preference

For me, despite the fact that I own a 16700, the best combination is 2001-2003 GMT Master II because:

  • Superluminova
  • SEL bracelet
  • Lug holes

Sinn 156 and Sinn 156b

MovementLemania 5100
Lug to lug51mm
Lug width20mm
MaterialStainless Steel
Water Resistance10bar
Service price600€-700€
Basic information

Sinn 156 is often referred as the successor of the Heuer bund, a watch used by German airforce pilots. Unlike the Heuer Bund, the Sinn 156 was never issued, as the era of pilot watches was already over by its release. Sinn 156b is a divisive pilot watch due to its size and movement. It is a large watch with 43mm diameter and 51mm lug to lug. Its movement, Lemania 5100 with central minutes, is considered a workhorse and provides an alternative for all the Valjoux 7750 powered chronographs.

Sinn 156 was in production for nearly two decades, and it came in two references 156 and 156b. Aside from the reference difference, there are a lot of variations, some which I will try to list in this post.

Dial, Bezel and the Movement

The dial layout of Sinn 156 is defined by the Lemania 5100 movement; three sub-dials and day/date. Chronograph hands are typically bright red. In contrast to Valjoux 7750, Lemania 5100 has central minutes, which leaves one of the sub-dials free from chronograph usage. The sub-dials are as follows:

  • (top) sub-dial 24h display,
  • (left) seconds dial,
  • (bottom) chronograph dial

All of the Lemania 5100s that I have owned have had distinct winding sensation and they are truly a pleasure to wind, serviced or not. The movement is considered a workhorse, but due to limited parts availability, I would not run unserviced Lemania 5100. The chronopushers of the Sinn 156 are similarly stiff to Valjoux 7750 and they make a satisfying crunch when triggered. The movement itself is not the prettiest.

The bezel of the Sinn 156 is anodized aluminium and it rotates smoothly both ways. The plastic crystal sits one to two millimeters above the bezel. The bezel develops wear just from rotation and winding the watch over time. The bezel is particularly vulnerable to contact with rocky surfaces. It is very typical to find watches where the paint has completely worn off from the sides of the bezel.

Worn paint at the side of the bezel.


Luckily, Sinn still has parts for the Lemania 5100 movement. The price of movement service of my Sinn 156 was 675 euros including shipping in December 2020. It is unknown whether Sinn has the capability to produce more parts for the Lemania 5100 and how long their parts supply will last. However, Sinn has produced watches with Lemania 5100 up until 2008, so it is possible that they have quite a bit of parts still left. Other manufacturers, such as Fortis and Tutima have had to stop servicing Lemania 5100, and Omega still has parts for their cal 1045, which was used at least in Speedmaster Mark 4.5.

The screw-down crown of the Sinn 156 is short, so one must take care not to break the threads. The crown of my Sinn 156b was replaced during service, and the replacement was identical. From parts scarcity angle, I’d say the overall serviceability of Sinn 156b is good.


The key difference between Sinn 156 and 156b seem to be the ‘Military’ print on the dial. Both Sinn 156 and 156b were produced with tritium dials, but Sinn 156b after 00s started to come with Luminova dials. The tritium compound on these watches seems to develop a very desirable orangish patina and it is rare to see watches with broken or tarnished tritium. To me this is a tell of good case construction.

The bracelet of the early 156s were the Sinn branded NSA bracelet. These bracelets are now very sought after and go on auction sites for over 600 euros. The later H-link bracelets are also rare to find loose, so it is best to buy a complete watch, if one intends to wear the Sinn 156 on a bracelet. I haven’t found a definite answer whether end-links from other watches will fit the Sinn 156 and it is best to assume they don’t. However, it looks like it is possible to file Sinn 103 end-links to fit the Sinn 156, but they won’t be a perfect match.

Most Sinn 156 and Sinn 156b came in a monocoque case, but some of the later Sinn 156b came in a screw-back case. The monocoque cases are interesting, since the case containing the movement is attached to the frame with screws that has the lugs. Some watches also have lug-holes, which in my opinion is a desirable feat in a watch.

TritiumSinn 156/Sinn 156b
Lug-holesSinn 156/Sinn 156b
‘Military’ print on dialSinn 156b
Screw-back caseSinn 156b
NSA braceletSinn 156
H-link braceletSinn 156b

Sinn 156 was also produced for Bell & Ross and there is a Beams version as well. Other manufacturers such as Hamilton and Bulova have produced a very similar watch, but it is unclear whether the Hamilton / Bulova watches were made by Sinn.


Sinn 156 is a big watch with a fun movement and cool looks. Depending on the configuration, it can feel very vintage to very modern. Watches with NSA bracelet and full tritium are the most sought after, but watches with luminova dials can make excellent everyday wearers. With the Sinn serviceability, the watch is relatively care-free.

Sinn 8820T


The 39mm Sinn 8820T comes in three different dial variants. Plain sterile dial, yellow U-Boat dial and red U-Boat dial. Unconfirmed information says that the U-boat dials were limited to 200 watches each and only for the Asian markets and the sterile dials were distributed globally.

MovementETA 2892-A2
Lug to lug45mm
Lug width20mm
Water Resistance200m
Basic information

The 8820T is special, because it is Sinn’s first full titanium watch and features a capillary depth gauge. The watch is also interesting, because it doesn’t have direct Heuer cousin reference like many other Sinn 80s dive watches.

My interest in the Sinn 8820T came after realising that Sinn 8820T has nearly everything the brands new lineup has. In a way 8820T is very similar to T2, but the watch also resembles Sinn’s other dive watches such as the U1/U50.

8820T, 801A, 805 and 809 aut

Despite being Sinn’s first titanium watch, the 8820T is only one of many Sinn’s 80s dive watches along with 801A, 805 and 809 aut. The 801A shares a case with Heuer 980.023 Deep Dive / Spirotechnique watches and comes with impressive 100ATM depth rating.

On the other hand, the 805 is built into a classic Monnin case and the 809 shares genes with Heuer 980.004. While the 801, 805 and 809 were both offered with automatic and quartz movements, it appears that 8820T was only available with an automatic movement. Without confirmation from Sinn, it is only possible to speculate the years the watches were produced.

Sinn ReferenceCase ManufacturerSimilarStart of production
Sinn 801Heuer 980.023,
Auricoste Spirotechnique
Late 1980s
Sinn 805MRP SAHeuer 980.006Early 1980s
Sinn 809MRP SAHeuer 980.004Late 1980s / Early 1990s
Sinn 8820TMRP SASquale 1535
Squale 1553
(Among others)
Mid 1980s
80s and 90s Sinn Diver watches.

The Case

The case of the 8820T is 39mm side-to-side, 43mm from lug-to-lug and 11mm thick. The size alone makes the watch invisible on the wrist. Combined with its titanium construction, the watch is both light and slim and wears extremely well on a nato strap. Like the 805 and 801, the 8820T is built into an outsourced case produced by MRP SA.

The Bezel

The bezel is machined into the case to protect it from accidental adjustment. To turn the bezel, user has to grip the bezel from sides and twist. The bezel has a painted tritium triangle at twelve o’clock position that can wear off. The numbers on the bezel are painted as well, making them subject to wear over time. The bezel action is sufficiently toolish and resembles Heuer references of the same era.

The Bracelet

The bracelet of the Sinn 8820T is made by the legendary Novavit SA (NSA). The bracelet itself is made out of folded titanium and resembles modern Sinn H-link bracelets, but rattles wiggles like a true vintage bracelet. The special feature of the bracelet is the patented NSA spring-loaded divers extension on the clasp. The NSA bracelets with this clasp offer instant micro-adjustment by spring-loaded pulling and recessing automatically. Unfortunately, this mechanism is subject to failure over time due to fatigue of the spring.

The NSA bracelet is a rare part and could be made out of unobtanium and thus it is very difficulty to source one. However, the bracelet is shared by Sinn 8827 and Sinn 8826. The end-links for these watches are different as the 8820 takes in less curving end-link, whereas the Sinn 8826 and Sinn 8827 have more curvature in the end-link. If you have the correct end-links, but a short bracelet, you can try to look for extension links (or message me because I have some and an extra clasp) or cannibalise a watch for its bracelet.


I queried about the service of the bracelet and the watch directly from Sinn. It looks like Sinn doesn’t have the crystals in stock anymore and water resistance cannot be guaranteed. Likewise, Sinn doesn’t have bracelets or their extension links for the NSA style bracelets. Communication from Sinn was good and exact, and they explained carefully what they will do to the watch. The final price of the service was aligned with the quote.

The service price list on Sinn site is reasonable. However, you will need to factor in shipping the watch. When serviced by Sinn, the service price is in the ballpark of 200-400 euros. The final price for my Sinn 8820T was 350€ including shipping costs. This included new crown, clasp spring and movement service. The service took over four months, but it is hard to make judgement here as I had a Sinn 156 sent there simultaneously.


Sinn 8820T can be considered a grandparent of Sinn T2 and perhaps even Sinn U50. The watch has a very distinctive look with its NSA bracelet. The watch is light and only 11mm thick making it virtually unnoticeable when worn. Due to the thinness, the watch wears well worn on a NATO although you may have problems fitting some of the thicker NATO straps due to the lug and spring-bar positioning.

The tritium compound on the dial and hands seem to age evenly, and makes a very pretty patina over time. This can be seen in many examples photographed online. The only downside is that the lug to lug of the watch is short, so it wears relatively small to those who have the big watch kink.

Fortis Easy Math Ref. 7242


Fortis Easy Math is a quirky 70s watch to the bone. The watch has a cushion case, two crowns and a busy dial. The dial has tritium plots, beautiful deep blue color, elevated disc with compass cardinal directions and a rotating slide rule bezel.

Lug to lug44mm
Lug width20mm
MaterialStainless Steel
Water Resistance5 ATM
Basic information

The stainless steel case has a beautifully sunburst finish with radially brushed surfaces and polished sides. A similar radial finish was used at the time by Omega in their various references among many others. The watch may look like a dive watch, but it is not and has a very modest depth rating.

The Dial and the Bezel

The most interesting aspect of this watch is the dial and the bezel. The bezel can be used perform multiplication and division operations by using the slide rule (and hence the name ‘Easy Math’). There is a lot of information online how to use the slide rule and how to use watch as a compass, so I will omit those.

The Case

The 37mm case is often advertised as 38mm by over eager sales guys to serve the big watch fetish. The case features two crowns, and is thus typically labeled incorrectly as EPSA super compressor. The EPSA super compressors feature a dive helmet and other EPSA markings on the case-back, but the EasyMath is missing those.

Example of EPSA Markings

The upper crown manipulates the internal slide rule bezel. and the lower crown winds the movement and sets time. The internal gear of the slide rule bezel crown is plastic. The same applies to the teeth on the bezel disk. When encountering mechanical resistance, one should probably avoid adjusting. Turning the bezel risks damaging the gear or the teeth. Replacement parts are unavailable.

The Movement

The manual FHF-ST96 movement is not particularly well regarded, but it is sometimes called workhorse movement. It operates at frequency of 18000A/h and has a power reserve of 48h. While it lacks many nice modern features, the only thing it left me yearning for is hack seconds.

The winding experience of the movement is smooth and the hands move precisely when time is set. While the FHF-ST96 is found in many fake / franken watches, I haven’t noticed that the Easymath is being faked. This would be unlikely due to the lack of market for the watches, but it would be a mistake to assume that something is too cheap to fake.


The unusual dial alone makes Fortis Easy Math worth collector’s interest. The movement is not haute horlogerie, but it gets the job done and at least feels nice to wind. Despite the modest technical properties and lack of complications, the watch feels excellent on wrist, looks great on a variety of straps and above all, you can find one for cheap. In the end, what more can you ask for?

Blushark Knitweave Review

The Blushark Orca is one of the best NATO straps I have had and I reviewed it very positively here. Based on the Blushark Orca, I had very high hopes for the Blushark Knitweave. The Blushark Knitweave straps come with either 20mm and 22mm width and are supplied with brushed hardware. The straps come in well known colors such as navy, khaki, green and black along with color combinations with highlight line.

The Blushark Knitweave straps are great on paper. They are keeperless, thin and seem perfect for a tool watch. However, in practice, the results are lukewarm at best. The strap could be slightly thicker, less glossy and slightly coarser and they would work much better for toolwatches. Due to the glossiness, the colors of the strap are slightly off. The khaki is too light and the army green is a little too deep. Consequently, the Knitweave straps sit somewhere between seatbelt-style and standard nato straps.

A word of warning: for flat watches where there isn’t much angle between the spring bars and the case back, the straps are somewhat dangerous due to the slickness. I nearly dropped my Tag Heuer 180.023 while taking the watch off, because the watch slid off the strap. The strap is also thin enough to justify a keeper. The straps are definitely for enthusiasts who enjoy thin straps.

I was initially hoping for a cheaper alternative to a Tudor-style nato strap, but I had hard time matching the straps with the watches in my collection. I can see that these straps could work with watches with colorful dials withand polished surfaces. Because of OK, but not great wrist comfort, the glossy texture and color and slickness, I have hard time seeing these becoming permanent choice for any of my watches. For people who enjoy thin seat-belt-style fabric straps, the Knitweave can be a welcome addition.

Sinn 158 on a bracelet


Sinn has made multiple successors to the 1550 sg produced by Heuer and Sinn. The Sinn 1550sg was directly succeeded by Sinn 156 and Sinn 156b and then followed by Sinn 155 and Sinn 158. Whereas the Sinn 155 is more true to the 1550 sg, the Sinn 158 sits somewhere between 1550 sg and 156b.

The elephant in the room is that neither Sinn 158 or Sinn 155 Darkstar was sold on steel bracelet whereas with Sinn 156 the bracelet was always an option. This leaves many Darkstar and Sinn 158 owners yearning for that cold hard steel on their wrists. The situation is bad, but it is not intolerable. Before the Darkstar and the Sinn 158, Sinn produced various watches with the reference Sinn 155. One of the came with steel bracelet.

First of the series is Sinn 155 ‘Manufactum’ with Valjoux 7750 movement. This was limited edition of 272 to the German market, sold via Manufactum. This watch features day/date chronograph seconds, minute register at top and hour register in bottom. I haven’t personally handled this watch, so I don’t know what the case is like. However, judging from pictures this is where the series begins.

The second entry to the series is Sinn 155 ‘Replica’, again a 300 piece limited edition made only for the Japanese market. The bracelet was optional for these watches. This watch features classic two register layout with minutes on the right and seconds on the left. Unlike the other versions, this watch uses manual wind movement. Judging from the packaging of the bracelet, the bracelet was supplied separately.

Middle Sinn 155 ‘Replica’, Right Sinn 155 ‘Manufactum’
(Photo used with permission of @milwatch_enthusiasts)

Finally, the third iteration before 158 is the Sinn 155 Darkstar collaboration with The Rake and Revolution magazine. Owners of these watches are in similar position as owners of Sinn 158. The Darkstar is very similar to the Sinn 155 ‘Replica’, but has automatic SW510 movement. Additionally, the Darkstar features a black star on the dial and faux lume, which makes it very attractive to those who want a modern equivalent to the Sinn 1550sg.

The Solution

The cases of Sinn 155/158 and Sinn 156b are not identical, so it is unlikely that the SEL bracelet of Sinn 156b will fit. The hollow end-link bracelet might, but until I have access to one, this remains to be a mystery. The solution for owners of the Sinn 155 Darkstar and the Sinn 158 is to acquire a bracelet for the Sinn 155 Replica. The cases of all these models seem to be identical.

In conclusion, the solution is not without problems. These bracelets are rarer than either Sinn 155 Darkstar or Sinn 158. However, they are a perfect fit. Those bothered by the Sinn 155 text on the bracelet can swap any bead-blasted Sinn clasp and have their nightly sleep. The end result is great and completes the watch.

View this post on Instagram

#sinn #sinn158

A post shared by @ ghostofgeraldgenta on

Tag Heuer 980.023 / 180.023 / 180.123 Review

Heuer (subsequently Tag Heuer) made some amazing dive watches. This review focuses on the dive watch which was in production for nearly 20 years in different variations and is known as ‘Deep Dive’ or ‘Spirotechnique’. This is certainly not the first post about this topic and definitely not the last.

Lug to lug46mm
Lug width20mm
MaterialStainless Steel
Basic information

The watch comes either automatic or quartz, with depth rating of 1000m or 200m and under various brand names. The distinctive features of the watch are its large bezel and crown at 4’o’clock.

The most famous incarnation of the watch is the variant known as ‘Spirotechnique’. This is a watch initially produced by Tag Heuer and later produced by Auricoste for the diving equipment company La Spirotechnique. This watch was issued to Marine Nationale combat divers and the issued watches are the most sought after pieces especially if they come with provenance such as decomissioning paperwork.

The other pieces don’t share the same fame, but have other merits. The other variants come either Tag Heuer or Heuer branded. ‘Deep Dive’ variant 980.023 boasts depth rating up to 1000m. The automatic version 180.023 has depth rating of only 200m can also have the Spirotechnique logo on dial. The ‘Nightdiver’, or reference 180.123 has full tritium dial, but is otherwise the same as the 200m automatic.

ManufacturerTag Heuer
Tag Heuer
MovementESA 536.121 
ETA 955.114 (N/L)
Thickness12mm (L)12mm (N/L)
Various references

The Dial

The dials of the different watches are nearly identical. They differ in branding, movement and whether it was produced for La Spirotechnique or not. The Deep Dive dial has a crystal retaining ring and extra gaskets which explains the extra depth rating.

All of the dials have tritium hands and indexes and no radium or luminova variants exist. I haven’t owned or handled the Heuer variant, but I wouldn’t hesitate adding one to my collection if one showed up.

The Movement

The ref 180.023 & 180.123 automatic versions use ETA2824, which is offers no surprises either positively or negatively.

The older Heuer branded quartz versions (980.023) use ESA movement, which can be difficult to source parts for in case of movement failure. However, the newer Tage Heuer branded ETA variants are replaceable quite easily and there are no worries from the maintenance perspective.

The Case

The case has uniformly polished finish and there is no play between polished / brushed surfaces. The bezel is a dominating feature of the watch as it is both big and tall. Despite of the polished surfaces, the watch pulls off that rugged tool-watch appearance that is very popular among vintage collectors today.

In spite of the relatively modern (read large) size, the watch wears comfortably. This is due to moderate lug to lug and low 12mm profile. My personal preference is a tall case back that extends bellow lugs and the non-Heuer variants lack this feature. However, it wears exceptionally well on nearly any strap or bracelet.

The edges of the lugs aren’t particularly defined, and the case is vulnerable to extensive polish. The crown side has two distinct surfaces and over polished cases typically loose the definition here. Same applies to the lugs, which also should have two distinctive edges diving the lug. On badly polished examples the lugs are nearly round and the definition is lost.

Polished case

Finally, the various references seem to have come with different crowns. Some of the 980.023N and 980.023L seem to have a smaller Tag branded crown whereas the crowns on the automatics seem to be larger. It may also be the watches I have handled have had service or aftermarket crowns.

The Bracelet

The standard bracelet to the watch is your typical Heuer / Tag Heuer diver jubilee with hollow end links. It is a comfortable bracelet, made out of good steel and a good companion to the watch. It is relatively hard to find these bracelets or extra links to them. Collectors looking to add add the bracelet to a rogue watch-head should be prepared to spend a pretty penny and significant amount of time on auction sites.

This is not going to be a popular opinion: the bracelet is is nothing special, and similar quality jubilee bracelets can be easily acquired if one suffers from the steel bracelet fetish and does not care about the originality. The bracelet is flimsy and rattly, but not in the good Rolex five-digit way. Both the deep dive and the Nightdiver are extremely versatile on a Nato strap and not being able to find a watch on the bracelet shouldn’t force anyone to skip the watch.


The Tag Heuer ‘Deep Dive’ or ‘Spirotechnique’ is a watch that works well on a nato strap. It is a versatile watch with very utilitarian look. It is susceptible to excessive polishing, but its maintainability is relatively good due to aftermarket parts producers such as tag1000diver. Even the ESA quartzes can be converted to more modern movements with some difficulty. As such, it is a vintage watch that can be worn, even heavily, which cannot be said from all vintage watches.


TAG Heuer 980.023N Deep Dive 1000m


Omega Planet Ocean cal. 2500, 42mm


Omega Planet Ocean (PO) line was introduced in 2005. The watches come in both 45mm and 42mm size and are famous for being worn by Special Agent James Bond played by Daniel Craig. In Casino Royale, Daniel Craig wore the 45mm planet ocean on rubber strap and in Quantum of Solace the 42mm 2201.50 on steel bracelet.

Movement2500 (ETA 2892-A2)
Lug to lug48mm
Lug width20mm
MaterialStainless Steel
Water Resistance600m
Basic information

The design of the PO draws from the history of the Omega Seamaster. The PO has a two part bezel found in pre-bond Seamasters and some of the earlier Omega references. The source of the bezel design is most likely Omega Seamaster 300 ref CK2913 produced in late 1950s. Another historic design choice is the curved lugs, which omega have been using since the appearance of first ST Speedmasters.

Various References

One thing worth mentioning is that the cal 2500 Planet Ocean has sharper case than the 2531.80 or 2254.50 Seamasters. While the lugs on the 2254.50 are similar, the form is considerably softer than on the Planet Ocean. This creates an impression of quality of the finish and a more modern look. I haven’t handled a modern unpolished Speedmaster myself, but it is said that modern Speedmasters have similar quality to the lugs.

It may be that all of the 2531.80s and 2254.50s that I have handled have been polished, but at this point, it would be extremely bad luck. Until otherwise proves, I’m going to assume that the edges on the older SM300 lyre lugs weren’t as sharp as on the PO lyre lugs.

Because of the many different color combinations, strap options and sizes, the following table attempts to summarise the reference numbers for 42mm Planet Oceans:

ReferenceStrapBezel colorIndex Color
2901.50.91Stiched RubberBlackWhite
2901.51.82Rubber (orange stitches)BlackOrange
42mm Planet Ocean References

The sheer number of available references may make finding the right watch to purchase difficult. However, it is a good idea to extend one’s searches as deals can be had in any of the references. Unfortunately sometimes dodgy sellers downplay the size and offer 45mm references as 42mm and this creates further confusion.

Bracelet vs Strap

As outlined earlier, the PO came in at least four different strap configurations: steel bracelet, steel mesh, stitched rubber and rubber. I have had pleasure to handle the non-sticthed rubber, and it is easily one of the best rubber straps I have had. It is both comfortable, doesn’t have the groce vanilla smell, which connoisseurs of poverty-grade rubber straps claim to be characteristic of nice vulcanised rubber. The strap doesn’t cause itch even when worn extensively.

The bracelet for the cal 2500 Omegas is 1580 / 952. Unfortunately, my watch never came with bracelet, so until I can source one second hand, I’m unable to review it. I know that the bracelet came with both pins and screws. As with 2254.50, a popular modification is to add micro adjustment clasp to the bracelet. More of this including the parts numbers can be found in the 2254.50 article.

1580/952Original steel bracelet
1589/858Steel bracelet from cal 8500
98000144Rubber strap
98000364Rubber strap from cal 8500
Available bracelets for cal 2500

The 1589/858 sits slightly too thick on the watch, but many prefer it because of availability and better clasp. The incorrect size of the 858 end link is especially noticeable where lyre lug meets the end-link itself. The rubber strap 98000364 also extends slightly above the lugs, but it is barely noticeable.

In addition to the steel bracelet and the rubber straps, the cal 2500 Planet Ocean wears well on a shark mesh. This is one of my personal favourites because the mesh is light and comfortable. The part number for the sharkproof mesh is 020ST1380237.

Hand Winding

The hand-winding experience of the cal 2500c is very nice and smooth. Unlike the 1120 or the Rolex Calibers, you can only hear a very faint sound of turning gears when hand-winding. In many watches, I would associate this winding to the wrong direction. Once wound full, just like the 1120, the movement gives nice pleasurable clicks to tell the winder to do something more productive with their life.

2500c vs 2500d

Anyone who is looking to buy any cal 2500 Omega watch is bound to find a lot of discussion over the differences of the movement. The differences have been discussed extensively. In short, the 2500d comes with three-tier escapement as opposed to the two-tier escapement of the 2500c. It is said online that the advantage of this is that the service interval of the 2500d is longer and the 2500d movement is less subject to failure due to wear or dislocation of the part.


The biggest misconception regarding the Planet Ocean 42mm is that it is a big watch. This is most likely caused by its 45mm cousin, or the newer 43,5mm versions. The 42mm PO wears slightly smaller than the flatter 2254.50 despite being taller. It also wears considerably smaller than Seiko MM300, which feels like a chunk of steel strapped to your wrist. On my 16,5cm wrist, the watch feels perfectly balanced on the rubber strap.

The various PO strap options, the two different movement types and the three different bezels/dials configurations can make the purchase confusing and somewhat difficult. Beyond the various references, the watch has a lot to offer: not many watches are simultaneously conservative (2201.50), playful (2201.51) and slightly obnoxious (2209.51).