Omega · Seamaster 120M

Strap for Seamaster 120M Quartz 41 Stainless Steel / Yellow Gold / White / Bracelet

Takes 20 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width20 mm
Case diameter41 mm
Reference2311.21.00
FamilySeamaster 120M
MovementOmega caliber 1538 hours, minutes, seconds | date | chronometer
Year1993
CaseYellow Gold, Stainless Steel

Recommended spring bar

Spring bars Omega 20mm — 1.8mm diameter

Technical match for lug width and diameter · lug 20 mm · Ø 1.8 mm

All Omega spring barsOpen →

Straps for the Seamaster 120M 2311.21.00

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Seamaster 120M 2311.21.00, seen from the bench

The Omega Seamaster 120M Ref. 2311.21.00 is a stainless steel and yellow gold two-tone watch introduced in the 1990s, featuring a 41mm case and a 20mm lug width. Powered by the Omega caliber 1538 certified chronometer movement, it displays hours, minutes, seconds, and date. With a water resistance of 120 meters, this model combines technical reliability with elegant aesthetics, making it suitable for recreational diving, snorkeling, and daily wear. The 20mm lug width ensures compatibility with a wide range of aftermarket straps.

Frequently asked questions

What is the exact lug width of the Omega Seamaster 120M Ref. 2311.21.00?

The lug width is 20mm, which is the distance between the case lugs that hold the strap at 20 millimetres. This width is standard on this model and is the essential parameter to identify compatible straps online.

Which type of strap pairs best with the Seamaster 120M bimetallic?

For a bimetallic yellow gold and steel case, an alligator in dark shades (black, brown, burgundy) emphasizes the robustness without competing with the gold. Alternatively, a vegetable-tanned calf creates elegant pairings and ages magnificently. For summer, shell cordovan offers natural rigidity without the weight of rubber.

How do I change the strap on my Omega Seamaster 120M?

Remove the original strap by identifying the two pins that hold it to the case. Use a tool called a spring bar removal tool (available online) to push the pins outward. Once the pins are released, the strap comes off easily. Insert the new strap by threading the pins into the new holes: the operation is simple if you perform it on a soft surface (a cloth) to avoid scratching the case.

Can I use an aftermarket strap on an Omega Seamaster 120M?

Absolutely yes. Aftermarket straps in 20mm are completely compatible with your Seamaster 120M. In fact, the artisanal market today offers options far more interesting than original straps: superior leather quality, shaped lugs, custom finishes. Just make sure the lug width is exactly 20mm, not 19mm or 21mm.

How long does a leather strap last on a watch worn daily?

A leather strap of artisanal quality worn daily generally lasts from 3 to 5 years, but it depends on frequency of use, exposure to moisture/heat and maintenance. With vegetable tanning it ages on purpose, developing patina and character; with chrome tanning it tends to degrade more rapidly. The 18-month warranty on Casati Milano straps covers any manufacturing defects and stitching.

The next step

The right strap isn't chosen. It is built, together.

From the atelier appointment to delivery, every step is made for those who know that things done well take time. Rare leathers, one piece at a time, eighteen months of warranty.

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Casati Milano · Via XX Settembre 15, Milan · by appointment only