Strap for Seamaster Diver 300M Co-Axial 41 GMT Stainless Steel / Blue / Bracelet / SBS

The Seamaster Diver 300M 2539.80.00 has a lug width of 20 millimetres. This specific width is the dimensional specification that determines the compatibility of any aftermarket strap. To measure correctly, insert a calliper or soft ruler into the space between the two lug attachment axes: the value must be precise to the tenth of a millimetre.

For the blue wave dial of the 2539.80.00, vegetable-tanned alligator in cognac or tobacco represents the most versatile option, creating natural aesthetic contrast and developing a golden patina over time. Black shell cordovan is ideal for sporting severity, while a NATO strap in nylon maintains the diving spirit in aggressive marine environments.

Strap replacement requires the use of a dedicated tool to push the spring bars that hold the strap to the lugs. Insert the small blade of the tool into the spring bar slot, push it laterally to release one end, then extract the spring bar. Repeat on the other side, remove the old strap and insert the new one, repositioning the spring bars. If you are not experienced, entrust the work to a professional watchmaker.

The deployant clasp (side-opening buckle) is not mandatory but is strongly recommended for the 2539.80.00. It keeps the strap securely on the wrist during diving and offers greater safety in environments where movement is intense. A traditional buckle works fine, but the deployant is the standard in the professional diving watch segment.

A quality leather strap (alligator or shell cordovan with vegetable tanning) typically lasts 3-5 years with moderate daily use, developing character over time. Exposure to salt water, chlorine and concentrated perspiration can shorten the lifespan; in this case, a marine elastomer strap is preferable. The warranty on an artisanal strap is usually 18 months.