Strap for Master Collection 29 Black Diamond / Bracelet

The lug width of the Longines Master Collection L2.257.4.57.6 is 15mm. This measurement represents the distance between the two lateral pins where the watch strap is attached. A compatible strap must have exactly 15mm internal spacing to ensure proper fit without play or excessive tension.

The ideal strap depends on intended use. For maximum formality, we recommend first-grade alligator with natural texture: it delivers elegance without excess and develops authentic patina over time. For daily robustness, vegetable-tanned calf offers superior grip and weather resistance. A NATO in cotton or canvas provides practicality and quick seasonal changes. Shell cordovan represents an intermediate solution with exceptional longevity exceeding ten years of constant wear.

The strap is replaced by extracting the lateral closing pins. Use a dedicated tool (spring bar tool) to compress the pin and withdraw it from the lug: this operation requires care to avoid scratching the case. The new strap is inserted by aligning one lug first, then compressing the pin and seating it in the opposite lug. For watches of significant value, we recommend professional replacement at a certified service centre.

Yes, absolutely. Provided the lug width is precisely 15mm, any artisan-made or industrial quality strap remains compatible. Milano Straps offers 15mm straps customisable in size, leather, colour and stitching details. The Casati Milano atelier creates bespoke straps with personal leather consultation and 18-month warranty, ideal for those seeking maximum constructive precision.

Lifespan depends on material, tanning and usage. Well-maintained alligator or vegetable-tanned calf guarantees 4-6 years of daily wear. Shell cordovan exceeds ten years of constant use. A NATO in canvas or cotton resists 2-3 years under intense use. Regular maintenance (gentle cleaning, protection from perspiration and humidity) significantly extends longevity. Artisan straps from Casati Milano, thanks to constructive quality and finishing, maintain optimal performance beyond the initial warranty.