Strap for Seamaster 120M Automatic 36.25 Yellow Gold / Diamond / Blue

The lug width of the Seamaster 120M 2105.45.00 is 18mm. It is important to measure it with a digital caliper between the spring bars, excluding the spring bars themselves from the measurement. This rare size requires specific straps, which are not interchangeable with common 20mm or 22mm widths.

For yellow gold like the 2105.45.00, we recommend light cognac or natural alligator, or vegetable-tanned calf leather in medium brown. These materials create harmony with the warmth of gold without chromatic conflict. Shell cordovan is a bolder and more formal choice, perfect if you seek tonal depth.

To change the strap, remove the spring bars using a specialized tool or spring bar removal tool. Position the tool under the spring bar from both sides, press gently to free it from the lugs, remove the old strap and insert the new one by sliding the spring bars into the appropriate slots. Ensure the spring bars click securely into the lugs with a crisp snap.

Any strap with an 18mm lug width is compatible. Our online collection offers 18mm straps in alligator, calf leather, shell cordovan and NATO, all customizable in color, size and stitching thread. It is important to always verify that the lug width matches exactly 18mm before purchase.

A high-quality artisanal leather strap, with vegetable tanning or alligator, typically lasts 3-5 years of regular wear. Longevity depends on frequency of use, ambient humidity and care. A shell cordovan strap, more durable, can last up to 7-8 years. We guarantee 18 months on our custom straps, but experience shows that artisanal leather ages magnificently beyond this period.