Omega · Seamaster 120M

Strap for Seamaster 120M Automatic 36.25 Stainless Steel / Silver

Takes 18 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width18 mm
Case diameter36 mm
Reference2501.31.00
FamilySeamaster 120M
MovementOmega caliber 1120 Hours, Minutes, Seconds | Date | Chronometer
CaseStainless Steel

Recommended spring bar

Spring bars Omega 18mm — single diameter

Technical match for lug width and diameter · lug 18 mm · Ø 1.8 mm

All Omega spring barsOpen →

The Seamaster 120M 2501.31.00, seen from the bench

The Omega Seamaster 120M ref. 2501.31.00, born in the 1990s, bridges heritage diving capability and classical elegance with a 36.25 mm stainless steel case and unidirectional rotating bezel. Powered by the Omega 1120 automatic movement with manual winding capability, it features a sapphire crystal, screw-down crown, and 300 metres water resistance certified as Master Chronometer. The 18 mm lug width is characteristic of this intermediate generation model, requiring precise strap selection to avoid tension issues or unwanted movement.

Frequently asked questions

What is the exact lug width of the Omega Seamaster 120M 2501.31.00?

The lug width of the Seamaster 120M 2501.31.00 measures 18 mm from shoulder to shoulder on the inner case. This dimension is critical for strap compatibility: even half a millimetre of deviation causes excessive tension or play. It is essential to verify the measurement before ordering the strap.

What is the best strap for the Omega Seamaster 120M 2501.31.00?

It depends on use and aesthetic context. Black alligator creates formal elegance and visual discretion; vegetable-tanned calf offers warmth and daily versatility, ideal if you desire an evolving patina; shell cordovan guarantees backlighting lustre and tactile density; NATO or rubber maintain submarine authenticity. The best choice reflects how you will wear the watch.

How do you correctly change the strap on the Omega Seamaster 120M?

Remove the spring bars from the lug hole with a delicate tool (plastic bar or dedicated tool), pushing from the inside outward. Once the lugs are freed, the old strap detaches. Insert the new strap and reintroduce the spring bars, ensuring they are fully seated in their slots. Verify that the strap is exactly 18 mm in width.

Can I use an aftermarket 18 mm strap on this Seamaster 120M?

Yes, provided the width is precisely verified at 18 mm from shoulder to shoulder. Quality artisanal straps custom-built often offer superior construction refinement compared to original Omega replacement straps and allow you to personalise material, colour and patina according to your aesthetic taste and context of use.

How long does a leather strap last on this watch?

A quality leather strap (alligator, vegetable-tanned calf, shell cordovan) maintains full functionality and aesthetics for 18–24 months of daily or regular use, with variability based on climate, personal perspiration and stresses. Vegetable-tanned leathers develop visible patina over months, telling the story of use. A well-constructed artisanal strap lasts far longer than standard industrial straps, with the possibility of regeneration or replacement of worn components.

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