Strap for Montbillant Black / Calf

The Breitling Montbrillant A4137012.B875 has a lug width of 20mm. This measurement is taken with a digital calliper positioned inside the two lugs of the case, perpendicular to the longitudinal axis of the strap. All compatible straps must match this width precisely to ensure correct fitting and zero play between strap and case.

Given the Montbrillant A4137012.B875's black dial and vintage instrument aesthetic, the most suitable materials are black or dark brown alligator leather, shell cordovan for maximum durability, and vegetable-tanned calfskin for everyday wear. A nylon NATO strap is the right choice for informal or sport contexts. The correct width is 20mm, with a stainless steel tang buckle or deployant clasp.

The strap on the Montbrillant A4137012.B875 is secured by standard 20mm spring bars. To replace it, use a spring bar tool: compress the spring bar ends, slide the strap out from the lug, and insert the new one. No case disassembly is required. The operation can be performed carefully at home or entrusted to a watchmaker or Casati Milano atelier.

Yes. The Montbrillant A4137012.B875 accepts any aftermarket strap with a standard 20mm lug width and spring bar fitting. milanostraps.it offers a curated selection of handcrafted straps in alligator, calfskin, shell cordovan and technical rubber, all made to 20mm and available in various lengths and colours. Build quality is comparable or superior to original Breitling straps.

The lifespan of a leather strap depends on material quality, frequency of use and maintenance. A high-grade alligator or shell cordovan strap, rotated with other straps and kept away from prolonged moisture and direct perspiration, typically lasts 3–5 years before requiring replacement. Vegetable-tanned calfskin straps generally need replacing every 2–3 years but develop a desirable personal patina over time. Casati Milano offers an 18-month warranty against manufacturing defects.