Strap for Chronomat 40 GMT Stainless Steel / Blue / Sylt

The lug width of the Breitling Chronomat 40 GMT (ref. A323986A1C1A1) is 20 mm. This measurement should be taken with a millimetre calliper at the inner distance between the two lugs, at the strap attachment point. The standard taper at the buckle end is typically 18 mm.

The most suitable options for the Chronomat 40 GMT are: alligator leather with vegetable tanning for a formal register with natural grain texture, smooth or padded calfskin for visual continuity with the stainless steel case, vulcanised rubber for active and sporting use, and dense nylon NATO for maximum everyday versatility. A stainless steel deployant clasp is recommended for security and aesthetic consistency with the case.

The strap is replaced via the spring bars connecting it to the case lugs. Using a fork-tipped spring bar tool, compress the spring bar, release the strap, and fit the new one. It is advisable to work on a soft surface to protect the case from accidental scratches. If in doubt, a watchmaker or the Casati Milano service can perform the swap professionally.

Yes. Any strap with a 20 mm attachment width and standard spring bars is compatible with the Breitling Chronomat 40 GMT. Milanostraps.it offers a selection of handcrafted 20 mm straps in alligator, calfskin, shell cordovan, rubber and NATO, produced with premium materials and finishes befitting a timepiece of this calibre.

Longevity depends on leather quality, tanning method and daily use. A high-quality vegetable-tanned alligator strap, properly maintained — kept away from water and occasionally treated with a neutral leather conditioner — can last between 3 and 6 years whilst retaining its appearance and function. Calfskin typically has a shorter lifespan of around 2 to 3 years with regular use. Casati Milano straps carry an 18-month warranty against manufacturing defects.