Strap for Speedmaster Moonwatch Co-Axial Diamond Side of the Moon

The lug width of this model is 21 mm. To verify it, position a caliper between the lugs internally: you will get exactly 21 mm. This width is specific to the 44.25 mm case diameter and ensures optimal proportions between mass and wrist.

For the black ceramic case we recommend dark brown or cognac alligator (warm contrast), vegetable-tanned black calfskin (minimalist), or anthracite grey rubber (sporty). The choice depends on use: formal, everyday, or adventure. What matters is a 21 mm strap with a proportionate keeper and, ideally, a robust deployant buckle.

You need a spring bar tool or assistance from a specialized watchmaker. Insert the tool into the thin lateral hole of the case, near the lug, to release the spring pin holding the strap: remove the old strap, align the new one (21 mm) and reinsert the pins. This is a delicate operation on a ceramic case: we recommend expert help.

All handcrafted straps with 21 mm lug width are compatible. On milanostraps.it you will find a collection dedicated to 21 mm straps, customizable in leather (alligator, calfskin, shell cordovan), rubber and fabrics. Atelier Casati Milano also creates bespoke straps with direct choice of leathers and 18-month warranty.

A premium leather strap (alligator or vegetable-tanned calfskin) typically lasts 4–7 years with daily use, depending on care, climate and wrist perspiration. Rubber lasts longer (8–10 years) but hardens over time. A vegetable-tanned calfskin strap ages developing natural patina, prolonging perceived beauty. Regular maintenance (cleaning, occasional conditioning) significantly extends durability.