Strap for Speedmaster 57 Co-Axial Stainless Steel / Silver

The lug width of the Speedmaster '57 is exactly 20 mm. This width is measured as the external distance between the two spring bars that emerge from the shoulders of the case. The 331.12.42.51.02.002 is proportioned to accommodate straps of this specific width, ensuring aesthetic balance between the 41.50 mm case and the lugs.

For the 331.12.42.51.02.002, alligator leather with vegetable tanning represents the luxury solution: the natural grain evolves over time and creates authentic patina. Shell cordovan is ideal if you seek extreme longevity and radical chromatic evolution. Vegetable-tanned calf offers superior comfort and rapid adaptation to the wrist, with elegant aging. NATO is a conscious choice for those who want to emphasize the chronograph's sporty character.

The 331.12.42.51.02.002 uses standard 20 mm spring bars. Remove them from the case using a thin lever tool (spring bar tool), gently leveraging on the curved terminals. Extract the pins from the case, then insert them into the new strap by aligning the lug holes. Reinsert the spring bars into the case until you hear the locking click. If you are not experienced, entrust it to a professional: the risk is scratching the case or losing a spring bar.

Yes. The standard 20 mm lug width of the 331.12.42.51.02.002 provides access to a wide catalog of artisanal straps. Always verify that the strap is sized for 20 mm width and that it has fittings (buckle or deployant clasp) suitable for your wrist. Custom straps from Casati Milano are made specifically for this lug width.

Durability depends on frequency of use and material. Vegetable-tanned calf, used daily with care, lasts 3–5 years. Shell cordovan can exceed 8–10 years if kept dry and protected from extreme humidity. Alligator lasts 4–6 years. Leather fears chlorine, intense salt sweat and prolonged sun exposure. Good maintenance—nightly drying, conditioning cream every 6 months—extends the life of the strap.