Omega
Speedmaster Broad Arrow 3651.50.31— lug 20mm

The lug width of the 3651.50.31 is 20 millimetres. This measurement indicates the width of the lug where the strap is inserted and is decisive for compatibility. To measure correctly, insert a rigid ruler between the two pins (upper and lower lug shoulders), verifying that the internal distance corresponds exactly to 20 millimetres. Do not confuse lug width with case diameter (42 millimetres): these are independent parameters.

For a chronograph in 18-carat yellow gold, we recommend alligator in vegetable tanning with intense cognac or shell cordovan in burgundy, which enhance the natural warmth of the precious metal through tonal dialogue and evolving patina. Deep burgundy vegetable-tanned calf leather offers an alternative formal gravitas. For sport-elegant contexts, an FKM rubber strap with embossed texture maintains the technical vocation without compromise. The choice depends on the use context: formal, daily wear, or sport.

Strap change requires removal of the spring bars. Use a spring bar tool to gently compress the internal spring of the pin, freeing one end from the case lug. Repeat the operation on the other side. Once the pins are removed, extract the worn strap. Insert the new pins into the replacement strap, ensuring that the retention balls are correctly seated. Compress the pin and insert it into the case lugs, verifying that the seat is secure on both sides. Be careful not to use sharp tools that could scratch the yellow gold lugs.

Yes. Specialised artisanal strap manufacturers offer 20mm straps in noble materials (alligator, shell cordovan, vegetable-tanned calf) that guarantee superior construction quality compared to standard OEM straps. The main difference lies in the choice of leathers (often sourced from excellent European tanneries), precision stitching and the possibility of customisation (sizing, initials, thread colour). A strap customised by a competent atelier offers durability and aesthetics comparable to or superior to original pieces, with the advantage of colour versatility.

The lifespan of a leather strap depends on three factors: quality of tanning (vegetable > chromatic in terms of controlled durability), intensity of use and environmental conditions. A high-quality vegetable-tanned strap, worn daily with minimal maintenance, lasts 2-4 years before showing significant signs of wear (cracks, thinning). A shell cordovan strap, thanks to the natural density of the fibre, easily reaches 4-6 years. Exposure to moisture, intense perspiration and thermal fluctuations accelerate ageing. Periodic maintenance with conditioning products specific to vegetable tanning significantly extends the strap's service life.