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Sinn U2

U2 (EZM5) Dive Watch (click to enlarge!)
U2 (EZM5) Dive Watch
© Sinn

Sinn U2 S (click to enlarge!)
Sinn U2 S
© Sinn

The Sinn U2 (EZM5) is a dive watch by Sinn.

The case of this dive watch is manufactured from submarine steel. Conventionally stainless steel for the watch case has no real resistance to sea water. Strictly seen such cases are not suitable for permanent use in sea water. In search of a steel, which meets the higher quality requirements, the Sinn engineers eventually made a find at the German submarine shipyard Howaldtswerke-Deutsche Werft and the Nordseewerke Emden/GmbH steel from the current German submarine production is exclusively delivered.

This material is not only extremely resistant to sea water, but has also the highest anti-magnetic quality. A residual magnetism still occuring in the conventional and high-quality stainless steel watch cases of grade 316 L, is not possible in the case of submarine steel.

Another major advantage of this steel for watchmakers lies in its special property to be tegimented. The submarine steel can be hardened to 1500 Vickers. Thus, the previous hardness of the Sinn tegiment case is exceeded by about 300 Vickers. For comparison, the base hardness of conventional stainless steel (316 L) is approximately 220 Vickers.

Another special feature of this watch is the captive and hardened diving bezel. To avoid removal of the rotating ring by hard knocks, it is not connected with the middle part of the case by a snap mechanism as usual, but a newly developed mounting device holds it securely in place. The detent is ball-mounted three times; slightly radially offset locking ball positions conserve the ring gear, ensure the function and provide a solid and secure engagement.


  • Mechanical movement ETA 2893-2, 28,800 A/h
  • Shock proof according to DIN 8308
  • Antimagnetic according to DIN 8309
  • Movement storage in a dry inert gas atmosphere, thereby improving the rate quality for a long time and extend service intervals
  • Safe operation from -45°C to +80°C


  • According to technical requirements of the dive watch standard DIN 8306
  • Submarine steel, bead-blasted
  • Ø 44 mm, height 15.45 mm
  • The case contains two dry capsules, one of which visibly filled at 6 00 h, with copper sulfate and provided with an overview of sapphire crystal glass. Dryness indicator white (dry) to blue (saturated)
  • Case filled with noble gas Argon, the most inert noble gas
  • Screw-in crown with 3 seals in series
  • Waterproof to 2,000 m
  • Safe below atmospheric pressure


  • Hours, minutes, seconds with hacking seconds
  • Date indication
  • Hour of the second time zone
  • Captive safety diver's bezel with luminous triangle


  • Black, indexes with special white, long-lasting luminous paint
  • Internal 24 hours scale in red
  • Hours and minutes hand black, with special white, long-lasting luminous paint
  • Central seconds hand in red, partially covered with white luminous paint
  • UTC hands black red lacquered


  • Silicone bracelet with diving extension or solid stainless steel bracelet, tegimented


  • 3 years
sinn_u2.txt · Last modified: 02.12.2022 20:43 by

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