Strap for Classic Field Jean Jacques Machado

The lug width of the B31SBN4RE1 is 22mm. This measurement indicates the internal distance between the two lugs of the case where the strap is inserted. We recommend verifying with a digital calliper that your strap falls within the tolerance of 21.8–22.2mm for secure and precise fitting.

The B31SBN4RE1, given its minimalist and military-inspired character, pairs perfectly with: alligator leather in black or dark brown for a classic finish; vegetable-tanned calf leather in neutral tones for refined everyday wear; NATO strap in regenerated textile for practicality and versatility; FKM technical rubber for extreme conditions or humid environments. Your choice depends on intended use: formal, casual, or adventure.

The B31SBN4RE1 features straight lugs with 22mm width. To change the strap: remove the watch from your wrist; use a spring bar tool (with a rounded tip) to depress the spring bars inside the lugs; gently extract the old strap; align the new 22mm strap with the lugs and apply slight pressure until the bars click into place. The operation takes minutes and requires no specialist knowledge.

Yes, any artisanal strap with 22mm lug width is compatible with the B31SBN4RE1, provided the actual width falls within the manufacturing tolerance (21.8–22.2mm). Milano Straps artisanal straps, crafted in alligator, calf leather and technical materials, have been tested on this model and ensure smooth insertion and long-term durability.

A quality leather strap—alligator or vegetable-tanned calf—typically lasts 3–7 years of daily wear, depending on intensity of use, sweat exposure and maintenance. A regenerated textile NATO strap lasts 5–10 years; technical rubber exceeds 10 years without perceivable degradation. Regular maintenance—gentle cleaning and periodic conditioning for leather—significantly extends longevity.