The tradition of watch brands collaborating with other brands, businesses, celebrities, and athletes is something almost as old as the history of wristworn timepieces itself. Whether it is Rolex jumping on the fabulous marketing opportunity to align itself with Mercedes Gleitze when she swam across the English Channel in 1927, Omega putting a Speedmaster ref. CK2998 on the wrist of astronaut Walter “Wally” Schirra in 1962 for its first space flight, or the numerous Swiss horology cameos at popular sporting events, for example when F1 pilots are handed over Richard Milles right before the post-race interviews. In all of these cases, it is major, luxurious houses of watchmaking taking front stage under the spotlights and both these watches, and the brands that make them, are out of reach to most of us. Luckily, in the more recent past, enthusiasts-driven online retailers have been embarking on more niche partnerships with iconic independent watchmakers to recreate iconic models we never had access to. 

This is the backdrop from which today’s review is going to unfold. We are about to dissect two extremely cool dive watches, originally exclusively made for the military, which any of us can now acquire to connect with a niche side of utilitarian horology some of us are deeply passionate about. The watch brand in question is the iconic Squale founded in 1959 by Charles von Büren and now run by the Maggi Family who historically distributed its watches in Italy, and the German-based, nerd-driven online retailer Chronofactum, from whom I borrowed the two watches in question for this article. (They also supplied the SUB-37 Legend we talked about a few months back.) Through this idyllic partnership is born the faithful recreation of a 1975 Blancpain Fifty Fathoms created exclusively for the German Underwater Commandos (West German Bundeswehr Kampfschwimmers), called the 3H Bund, which was outfitted with the Squale 1521 “50 Atmos” case. Itself a proper legend. The new collection is the date/no-date 1521 UCB*. 

*The UCB nomenclature refers to “Uhrforum Chronofactum BUND” where Uhrforum is the German watch forum Chronofactum developed this model with. 

Specifications 

The original Blancpain Fifty Fathoms Bund is the stuff legends of utilitarian horology are made out of. As you might be aware, Blancpain is credited by many to have released the original professional-driven modern dive watch (before Rolex’s Submariner,) allegedly the first to be equipped with a rotating bezel, legible luminous markers, and relatively excellent water resistance for the time period—1953—of 100 meters (that is what 50 fathoms equals to.) Shortly after its creation, in the 1960s, Squale started supplying dive watch cases to iconic brands such as Heuer, Doxa, Dodane, Airain and Blancpain, as the brand specialized in the fabrication of this crucial part of underwater exploration timepieces. This is when Charles von Büren engineered the iconic 1521 case, also known as the “50 Atmos” case because it was the first to boast 500 meters of water resistance which was a real technical feat for the time. Thus, in 1975, the German Military turned to Blancpain to equip its underwater commandos with a robust and legible diver.

The Blancpain Fifty Fathoms 3H Bund was named so after two facts: “H3” is the military reference to tritium-coated markers and hands, which was printed in a red font below the pinion (we will go back to later on,) and “Bund” is short for “Bundeswehr Kampfschwimmers” where Bundeswehr refers to the unified German armed forces and Kampfschwimmers translates to combat divers. This is where the single-marker dive bezel commonly known as “Bund Bezel” comes from, since German underwater commandos would deploy for multi-hour missions and needed to be able to track elapsed hours instead of minutes, thus a single triangular lumed element was necessary. The Chronofactum x Squale 1521 UCB is a faithful, albeit technically modernized recreation of the 3H Bund which comes in both date and no-date variants to satisfy all military dive watch nerds out there. The collection is evidently outfitted with the modern iteration of the Squale 1521 case which measures 42mm in diameter, 48mm lug-to-lug, 12.5mm thick, and comes with a 20mm lug width. 

This case, friends, is physically quite substantial albeit in a positively watch enthusiastic manner, for it weighs 118g on the FKM rubber strap and 155g on the steel bracelet sized to my 6.50”/16.5cm wrist. It doesn’t come with the same weight as an Omega Ploprof of course, however it has been many moons since I’ve experienced this kind of nerdistic weight on the wrist which I just realized I have been seriously missing. As it was back then as it is today, the 1521 boasts 500 meters of water resistance which is ensured by way of a tall screw-down case-back and a four o’clock screw-down crown which measures a reasonable 5.7mm in diameter. The bezel the Blancpain Fifty Fathoms 3H Bund was known to have comes here in a unidirectional setup complemented by 120 precise clicks, a profound absence of backplay, and is secured to the case housing by way of four screws to ensure it doesn’t accidentally come off. For the same reason of safety, Charles von Büren had placed the crown at the four o’clock to prevent accidental knocks. 

Evidently, the tritium luminescent compound was replaced by a non-radioactive one, here SuperLuminova C1 which looks white during the day and glows bright green at night (the same glow as the radioactive H3), applied in generous quantities on the hands, printed hour markers, as well as the triangular marking on the bezel—which is why the indication of “H3” was replaced by “C1” below the pinion, a neat little detail. Inside the iconic case, we find an Élaboré Sellita SW200 caliber (4Hz/38 hours of power reserve,) regulated by the manufacturer in three positions to run at ± 7 seconds per day, and which Squale offers in no-date (without a ghost-date position) and date variants. Lastly, Squale and Chronofactum offer you a few options for fastening systems: either a combo of two black rubber straps, the Von Buren Pro strap and a Tropical rubber one, or the three-link steel bracelet paired with either the Von Buren strap or the Tropic one. I highly recommend the Von Buren strap over the Tropic for its great styling and comfort. 

Speaking of the bracelet: it is equipped with short screwed links and a double-pusher deployant clasp complete with an old-school safety latch (I also sorely miss on most modern dive watches) and four holes of micro-adjustments. 

Design

Even though it would be fair to assume that many of you enthusiasts, collectors, and nerds came to this review primarily because your horological heart was moved by the beauty of the Squale x Chronofactum 1521 UCB (as well as its historical significance,) you might be impressed to discover the comprehensiveness of its technical specifications. After all, it was originally created from highly capable cases and made in collaboration with a Swiss brand that has a long history of making professional grade tool watches for an elite German military unit, so it should come with little surprise to see how capable the 1521 UCB is. More than that, and even though you can only take my word for it if you haven’t had the pleasure of seeing this collection in the metal, it is superbly manufactured and finished, and there has to be a secret or two as to why the case weighs so much, however pleasurable that weight is, for it is an integral part of the wearing experience and one of its welcome feature. But how gorgeous that thing is, right? 

Through a small confession—this is, I believe, the first 1521 case I spent more than 30 seconds with—I would move into a disgustingly positive description of that chassis I have now converted to. What made the 1521 special in the 1960s and still makes it so in 2026, besides its 500 meter depth-rating, is the sculpted nature of its profile and how it was perfectly designed so that its perceived tall figure purposefully wraps around the wrist akin to an octopus anchoring its tentacles around a harpoon. While the left flank of the case shoots straight down, the right side is composed of a flat surface which must exist in order for the case to accommodate the four o’clock position which is partially recessed within it. Despite the asymmetrical flanks, the case disappears below the wild bezel, the latter composed of a fine coin-edge finish, a polished circular chamfer, and a PVD-coated aluminum inlay for that vintage look and modern robustness. And the lugs—man—wide, doubly-chamfered, angled down akin to the feet of an excavator. 

The 1521 case is legendary amongst dive and utilitarian watch enthusiasts and now I understand why. It is a marvel of horological engineering and design and it is quite fabulous that Squale still manufactures it. But but but, what about the dial you may ask? Quite spedenlicous in its own right, superbly legible on account of the deep matte black dial, clean-white applied hour markers and minute dashes, surrounded by a fully mirror-like polished rehaut which virtually enlarges the circumference of the dial and enhances its legibility by giving the impression that a second set of hour markers lives beyond the minute track. This is a design trick I’ve not encountered before—as far as my aging memory recalls—and which is quite clever. Moreover, the hands are in the traditional Squale aesthetic, shaped like taper-less wide batons, a white hour hand, an orange minute hand, and a thin seconds hand entirely painted white with a lumed lollipop element. And of course, the historical-nod “C1” printed in blood red ink below the pinion. 

The Heart of the Matter

For those of us who are addicted to tool watches or dive watches or military watches or a combination of all three of those, there are but a few models we had wanted to see resurrected. For example, we might wish to see one day Rolex re-issue a MIL-SUB Submariner, even though this won’t ever happen because Rolex doesn’t give a rat’s ass about what we want. Or we dream to see Blancpain recreate the 1953 Fifth Fathoms and its ultra-vintage utilitarian charm and incredible wrist presence. However, this is unlikely to happen as well. Luckily for us, once in a while, a brand and or a brand in partnership with another entity decides to make a niche military timepiece that was once only available to professionals—as in not commercially available to the wider public—at the reach of civilians, and more specifically, the highest-level of watch nerds such as yours truly. Which is why writing about the Chronofactum x Squale 1521 UCB was a treat, not only because I’ve never spent quality time with a 1521, but also because the Blancpain Fifty Fathom 3H Bund it was designed after was a de facto legend. 

In other words, this collection is everything that a dedicated community of our global community have been asking and waiting for, and that is actually two things: the faithful recreation of a vintage icon of military submersible history, celebrating its past relevance and legendary design; the re-issuing of a certain type of diver now made available to the public which showcases a relatively ultra-simple and paired-down dial layout a bit uncommon for our horological zeitgeist (which privileges textured and colored dials.) And this could only have been possible by a dual partnership—between Squale and Chronofactum, and between the latter and a watch forum. In other words, two enthusiast-driven entities from which comes a collection of two divers filled to the brim with utilitarian horological goodness.

Conclusion 

The Chronofactum x Squale 1521 UCB comes in two versions: the date one which offers a tad extra functionality for those who like to have it; and the no-date version for those who prefer a cleaner look. If I were to be asked to choose between either versions I do not know what I would do as both are equally seductive. What is also attractive about the 1521 UCB is the fact that it is readily available on Chronofactum’s website for the price of €1,490/$1,739 USD in the two rubber straps configuration and €1,690/$1,973 USD in the bracelet + strap variant. Given the history of the model it was designed after, the legitimacy of Squale’s in purveying some of the best watch dive cases to iconic names of the industry, and the UCB’s excellent spec sheet and utilitarian design, one must go through an internal struggle not to pull the trigger on it. 

Moreover, if you’re an inhabitant of the Old Continent, I suggest taking a closer look at the brands Chronofactum carries here. 

Thanks for reading.