Seamaster 300 Master Chronometer Stainless Steel / Black / Bracelet

In Context

At 41 mm it is sized to the current mainstream: 40 mm is the median across every watch measured in this catalogue. At 13.85 mm it is a tall case, and it will catch on a cuff. The case back is open, so the movement is visible without taking the watch apart, and the sapphire crystal will resist everything short of deliberate abuse. 300 m is a professional diving rating, far past any demand a wrist is likely to make of it.

The movement winds itself from the motion of your wrist. 60 hours of reserve is enough to set it down on Friday evening and find it still running on Monday. At 25,200 vph the seconds hand advances 7 times a second.

234.30.41.21.01.001 stands on its own in this catalogue — no other reference here shares its base number. It pairs a black matte dial with a aluminium, stainless steel case. Introduced in 2021.

The 8912 is the 8900 without a date, Omega's two-barrel Master Chronometer movement with the calendar left out. It is made for the divers whose dials the 1957 originals drew. It powers 28 watches in this library. The [8900](/calibers/omega-8900) is the co-axial caliber certified by METAS to 15,000 gauss, with two barrels in series for 60 hours, a silicon balance spring on a free-sprung balance and a beat of 25,200 vph; the 8912 keeps all of it with 38 jewels at 29 mm across and no date window. The 8913 is the same movement with a gold rotor and balance bridge. In the library it powers 16 [Planet Ocean](/brands/omega/seamaster-planet-ocean) references, the Ultra Deep 6000 m of 2022 at 45.5 mm and the 42 mm models, 6 [Ploprofs](/brands/omega/seamaster-ploprof) at 55 mm and 6 references of the 2021 [Seamaster 300](/brands/omega/seamaster-300). Cases run from 41 mm to 55 mm. The [8806](/calibers/omega-8806) is the single-barrel no-date movement for mid-size cases, and the glossary covers the [Master Chronometer](/glossary/master-chronometer) standard.

27 other watches in the library run the Omega 8912.

Omega

Seamaster Planet Ocean Ultra Deep O-Megasteel / Summer Blue / Bracelet

215.30.46.21.03.002 · 45.5 mm

Omega

Seamaster Planet Ocean 600M Co-Axial 42 Stainless Steel - Black / Black / Rubber

217.32.42.21.01.001 · 42 mm

Omega

Seamaster PloProf Co-Axial Master Chronometer Grey / Orange

227.90.55.21.99.002 · 55 mm

Omega

Seamaster PloProf Co-Axial Master Chronometer Titanium / Sedna Gold / Blue

227.90.55.21.99.001 · 55 mm