For reasons I am sure you can entirely understand, I’ve always referred to Sinn’s 903 collection of pilot chronograph watches as “Sinn’s Navitimer.” While the awesome tool watchmaker from Frankfurt, Germany typically has more distinctive designs (though some of their watches fit historic design rubrics, for sure), the 903 family of chronograph watches with a slide rule bezel has always looked very much like the Breitling Navitimer. Sinn has just released the “903 St II,” which upgrades the core 903 family. However, the collection has not changed the fundamental “Sinn Navitimer” formula. Understanding the history of Sinn and the 903 collection sheds illuminating details on why this model exists and also why it is one of the better-kept secrets in historic-style professional sports watches.
The Sinn 903 St II debuted in 2024, a few years after the original 903 collection was discontinued. Sinn had worked on a major refresh to the 903 (that would become this 903 St II) which didn’t fundamentally change the theme or aesthetic but simply made the core concept better in terms of design and functionality. According to Sinn, when the company first started in 1979, it purchased a lot of new old stock parts from Breitling (a lot of such parts were available at the time). This allowed the brand to make its own slide rule-style pilot chronograph watches, similar to the popular Breitling Navitimer. Even though the “Navitimer” name is clearly owned by Breitling, there is nothing inherently protected in the core Navitimer design that other companies cannot use. Probably the only reason there aren’t more Navitimer-style watches out there is that getting this product right is a challenge, as evidenced by how long Sinn took to get to this point.
I think it is further important to add that while the 903 St II is intended as a professional-use tool watch, the number of pilots out there who want (or understand how to use) a slide-rule bezel watch is very small. This type of timepiece should probably be thought of as a high-quality emulation of a vintage tool that is charming and pretty but isn’t designed for most modern aviation purposes. Of course, there is the fact that German Sinn’s offering is also far more affordable than Swiss Breitling’s option. I wouldn’t compare the products on a 1:1 basis, but there are clearly going to be people who feel that Sinn’s 903 St II has everything they want and that Breitling’s more expensive products might not offer too much more to make up for the considerable price difference.
The particular version of the Sinn 903 St II that I am reviewing today is the 903 St BE II on the brown alligator-style leather strap. The “St” part of the name probably refers to the steel case construction and the “BE” part of the name references this deep blue face with its silver/white subdials and outer slide rule calculator ring. Sinn also produces a similar black-dial version (also with silver subdials), as well as a lighter blue-dial version. I suspect that, in time, more dial colors and styles for the 903 St II collection will become available.
I’ve always been intrigued by this dial design (for Breitling or Sinn) because although it suffers from being very busy and is harder to read, it still ends up looking attractive and cool. The Navitimer-style dial does have proportionally proper hands, but the dial for the time is comparatively small when looking at the larger face with its outer data scales. The hardest thing to do on such a dial is immediately recognize the hands and hour markers for time reading. Of course, there is the fact that nearly no one uses the slide rule bezel and that operating it is more akin to a fidget device than a useful tool. Perhaps less than ironically, Sinn worked very hard on improving those two areas in the 903 II watch over the classic 903.
Size-wise, this is a very sensible watch intended for as broad a spectrum of wrists as possible. In fact, it makes sense that the size of the 903 St II is more sensible given the desire to connect these to more vintage designs. In addition, there’s the fact that Sinn has historically done very well with the 903 in markets such as Japan and other parts of Asia which at least historically have preferred modest to smaller case sizes. The 903 St II’s finely made polished and brushed steel case is, accordingly, 41mm wide, 14.5mm thick, and 48.5mm lug-to-lug. Over the dial is a slightly domed AR-coated sapphire crystal, and the case water resistance is 200 meters (up from 100 meters for the original 903).
One of the most important features of the 903 II is that the bezel now operates like that of the Breitling Navitimer. The classic 903 watches looked the part but they did not have a turning bezel you could turn with your fingers like the Navitimer. Instead, the watches used a crown located at the 10 o’clock position to turn an internal rotating bezel — similar to some diver’s watches. Sinn entirely reengineered the 903 case and bezel to support the more ideal functionality that allows users to turn the outer bezel, which operates the inner bezel. What is impressive is not only how nicely the smooth-yet-firm turning action of the bi-directional bezel is, but also how Sinn’s design is appreciably more water-resistant than that of Breitling.
To make the dial more legible, Sinn decided to work on the hands and hour markers to make them more prevalent. The result was using “hybrid ceramic” solid lume applied hour markers, with matching hands. The raised hour markers make them much more visible and thus allow for a more legible watch. The lume elements also glow really well, making a strong case for Sinn and other companies to keep investing in solid luminous materials as opposed to more historical paints and other applications. Another addition to the 903 St II over the 903 is the use of an applied Sinn logo. Otherwise, the dial of the 903 St II watch is very much the classic slide rule scale chronograph style that has been around for years – which is exactly what the market seems to want.
Sinn moves away from Swiss Made Sellita for the movement in the 903 St II and instead works with Swiss Made La Joux-Perret (owned by Japan’s Citizen Group). The movement is the caliber LJP L112, which is an automatic 12-hour chronograph with a date complication. The chronograph uses a column-wheel transmission system (visible through the caseback and colored blue) while the movement operates at 4Hz (28,800 bpm) with a very decent power reserve of 60 hours. Clearly, Sinn is trying to edge closer to the features and performance of Breitling’s in-house B01 movements. The movements are also anti-magnetic to DIN 8309 standards. Overall, I really like the use of these movements, since La Joux-Perret now offers a very good mixture of performance, decoration, and value. The overall movement presentation through the rear sapphire crystal window is well done as well.
Clearly, the Sinn 903 St II is a major upgrade of the 903 and makes an attractive package even nicer. Sinn improved the case, movement, and dial while offering a price-to-features ratio that is rare (to say the least) in the established watch industry today. A similarly-equipped Breitling Navitimer is also an excellent watch, but at least double the price of what Sinn is asking. For example, a 41mm-wide Breitling Navitimer with the brand’s in-house B01 automatic chronograph movement costs (as of writing) about $9,500 USD. Even on a matching steel bracelet, the Sinn 903 St II costs less than $4,000 USD. That is a considerable difference, especially when taking into consideration how reliable and trusted Sinn timepieces are. Sinn won’t have the branding recognition or distribution that Breitling has, but for people who want a product, a story, and an engineering accomplishment, Sinn probably has everything they want (and a bit more) in a product like the 903 St II.
The most cynical way of looking at the Sinn 903 St II (as a product that rides the coattails of demand that another company created) doesn’t really erode its desirability much. If product originality is strictly what you are seeking, then you probably aren’t in the market for a vintage-themed pilot watch, anyway (as most of them follow established rubrics or design styles). Sinn has other watches for that. If you have always been interested in a slide rule bezel chronograph watch and like what Sinn is offering, then this is a very attractive package for an amount of money that feels downright affordable compared to what many other watchmakers are charging today. Despite the quirks of the underlying design I mentioned above, the 903 II watch is handsomely conservative in style, very well-made, sports some novel technology, comfortable to wear, and will probably be relevant one or two decades from now as part of your collection. This isn’t the Sinn I would grab first given what I most admire in the brand, but it is a very good watch that I enjoyed wearing and found to be quite fashionable. It also ties in nicely with Sinn’s history and is not a mere “lookalike” product. Price in the United States via Sinn’s dealer, WatchBuys, for the 903 St BE II watch on the leather strap is $3,730 USD. Learn more at the Sinn website.
Necessary Information:
>Brand: Sinn
>Model: 903 St BE II (as tested)
>Price: $3,730 USD
>Size: 41mm wide, 14.5mm thick, 48.5mm lug-to-lug distance
>When reviewer would personally wear it: As casual daily wear vintage-style sports watch that is very reliable and conservative in style.
>Friend we’d recommend it to first: Lover of what Sinn offers the market, who has been wanting to experience the style of a slide rule bezel, chronograph pilot’s watch.
>Best characteristic of watch: Impressive upgrades over the previous-generation model make watch prettier and a better tool. Good dial legibility given overall theme. Comfortable and well-priced.
>Worst characteristic of watch: A cynical person could deride this product as a mere Breitling Navitimer homage.
