Sinn Introduces the U50 Dive Watch

The submarine steel diver, now mid-sized.

Sinn‘s signature dive watch is the near-indestructible U1 that’s a large 44 mm in diameter. Now Sinn has unveiled the mid-sized version of the same, the U50, which offers all of the goodness of its bigger brother but in a 41 mm case.

Initial thoughts

I am a fan of the original U1 because it is seriously minded in its functionality, encompassing design, material, and testing. And it is affordable, making it great value for money.

The new U50 has almost all of the same features and similar pricing, so it is hard not to like it.

But one caveat: though the U1 is a largish 44 mm, it never really felt that large, perhaps because of the short lugs and wide bezel (thus a small dial). So while the U50 may fit better on some wrists, it might look smaller than its 41 mm diameter suggests.

U50 at 41 mm (left), and U1 at 44 mm

Super steel

Like the U1, the new U50 has a case made of submarine steel, the same alloy used for the German navy’s submarines. Highly resistant to seawater corrosion and also especially nonmagnetic, the steel alloy comes from ThyssenKrupp Marine Systems, a builder of naval vessels, and is the same material used for the hull of the stealthy U212 class of submarines.

It’s rated to 500 m – hence the U50 moniker – and powered by the no-nonsense Sellita SW300-1, a clone of the ETA 2892. That’s less than the 1000 m of the U1, but 500 m is still plenty – and about the same depth rating as most navy submarines.

And if the submarine steel alloy alone wasn’t robust enough, the bezel of the U50 is also treated with Tegiment, Sinn’s proprietary hardening process that leaves it almost scratch-proof (the U1 boasts the same treated bezel too).


Like the U1, the U50 is available in three guises: straightforward all-steel, a steel case with a black-coated bezel known as the U50 SDR, and also the all-black coated U50 S.

From left: U50, U50 SDR, and U50 S

The U50 S is substantially more expensive, but for good reason. Unlike the U50 and U50 SDR that have Tegiment-treated bezels, the entirety of the U50 S is Tegiment hardened. That means the bezel, case, and back of the U50 S have an extra-hard surface that is then bonded with a highly-resistant black coating, resulting an exceptionally robust watch.

Key facts and price

Sinn U50
Ref. 1050.010 (U50)
Ref. 1050.020 (U50 S)
Ref. 1050.040 (U50 SDR)

Diameter: 41 mm
Height: 11.15 mm
Material: Submarine steel
Water resistance: 500 m

Movement: Sellita SW300-1
Functions: Hours, minutes, seconds, and date
Frequency: 28,800 beats per hour (4 Hz)
Power reserve: 42 hours

Strap: Rubber strap or steel bracelet

Limited edition: No
Availability: At Sinn retailers
Price: U50 – €2,160; U50 SDR – €2,230; U50 S – €2,600 (prices for watch on rubber strap, include German VAT)

For more, visit

Correction April 30, 2020: The SW300 is a clone of the ETA 2892, and not the ETA 2824 as stated in an earlier version of the article.

Back to top.

You may also enjoy these.