Strap for Master Collection 40 Moonphase Stainless Steel / Silver-Diamond / Alligator

The Longines Master Collection L2.909.4.77.3 features a lug width of 21mm. This dimension allows for the installation of bespoke and aftermarket straps specifically sized for 21mm lugs. Always verify this measurement before purchasing a replacement strap to ensure mechanical and aesthetic compatibility with the case.

For the Master Collection L2.909.4.77.3, we recommend high-quality alligator or calf leather straps for formal occasions, as the classic case design demands refined elegance. For sporty casual wear, woven NATO or vulcanised rubber are versatile options. Vegetable-tanned leather develops a natural patina over time, transforming the strap into a living element that evolves with use.

The lug width is measured by calculating the distance between the two internal attachment points where the strap connects to the case. For your Longines, use a digital calliper and measure perpendicularly between the lugs. The construction tolerance for 21mm may vary by ±0.1mm; we recommend contacting Casati Milano for in-studio verification with professional tools.

Yes, absolutely. The artisanal straps from milanostraps.it are manufactured to 21mm specifications and can be mounted on your case lugs without requiring additional mechanical interventions. The construction quality of our premium leather straps ensures durability exceeding OEM alternatives. The Casati Milano atelier provides personalised guidance on leather selection and finishing options.

A natural leather strap, if crafted from premium materials (alligator, calf, shell cordovan) and maintained correctly, will provide 4 to 7 years of service before requiring replacement. Vegetable-tanned leather develops a distinguished patina over time, enhancing aesthetics. The Casati Milano atelier offers an 18-month warranty on bespoke straps and provides seasonal maintenance advice to preserve structural integrity and visual character.