Strap for Master Collection 42 Moonphase Stainless Steel / Black-Roman / Alligator XL

The lug width of the Longines Master Collection L2.919.4.51.8 is 21mm. This measurement is taken on the inner side of the case where the strap is inserted. It is a specific dimension requiring bespoke, artisanal straps not found in standard catalogues.

For this model, a deep brown alligator or black vegetable-tanned calf is recommended. Alligator offers a refined grain that dialogues harmoniously with the faceted case geometry, whilst vegetable-tanned calf develops a natural patina that emphasises the dial's dignity. Selection depends on daily use and personal aesthetic preferences.

Remove the strap by extracting the spring bars (metal pins) from the lugs using a spring bar tool or dedicated extractor. Position the watch on a soft surface, locate the small hole where the pin passes through, apply gentle pressure to extract the pin, and slide out the old strap. Align the new strap's holes with the lugs, reinsert the pin until it clicks. If uncertain, consult a professional watchmaker.

Yes, provided the strap is compatible with the 21mm lug width. milanostraps.it offers artisanal 21mm straps in stock, crafted from alligator, calf and premium leathers. For a fully bespoke strap—custom shape, colour, initials and stitching thread—Casati Milano atelier creates made-to-measure solutions with direct consultation and an 18-month warranty.

Leather strap longevity depends on tanning quality and daily wear patterns. A quality alligator strap typically lasts 4-5 years with standard care; vegetable-tanned calf, owing to its natural porosity, evolves in character and remains functional for 3-4 years. FKM rubber offers greater durability (6-8 years) but lower aesthetic versatility. Store straps in dry conditions and clean regularly with a soft cloth.