Strap for Master Collection 42 Moonphase Stainless Steel / Silver-Arabic / Alligator

The lug width of the Longines Master Collection L2.919.4.78.3 is 21mm. This measurement represents the distance between the two terminal holes where the strap attaches to the case. It is a non-negotiable construction specification for this model: Longines has dimensioned this lug width to maintain optimal proportions with the 42mm case diameter.

The best strap depends on intended use. For formal everyday wear, we recommend natural alligator with vegetable tanning (patina development, natural leather breathability). For ultra-formal occasions, polished alligator. For casual-business wear, Italian or Swiss calf leather with visible texture. For summer or sport use, robust cotton NATO or vulcanised rubber. A conscious ownership strategy involves two straps: one in vegetable-tanned leather for daily use, one in alligator for formal occasions.

The strap is changed via the spring bars located at both ends of the case. Using a dedicated tool or small flat-head screwdriver, apply gentle pressure inward to compress the internal spring, releasing one end of the strap. Once the original strap is removed, insert the new strap in the same manner, ensuring the spring bar clicks firmly into position. Never force: the motion must be fluid. We recommend having this operation performed by an authorised Longines service centre if you are unfamiliar with the procedure.

Yes, provided the lug width is 21mm. Not all aftermarket straps respect Longines dimensional standards: tolerances exceeding 0.5mm can generate vibration or shine marks at contact points. We recommend straps produced by artisans specialising in larger lug widths (21mm, 22mm, 23mm) such as those available on milanostraps.it, where each piece is constructed to millimetre precision and customisable in leather type, measurements, and stitch thread colour.

Lifespan depends on leather quality and usage patterns. A high-quality alligator strap with vegetable tanning lasts 4–8 years in daily wear, developing a patina that increases aesthetic value. A calf leather strap lasts 3–6 years. Wear typically manifests first at the buckle contact zone (lacing due to entry/exit from the loop) and in continuous flexing at the spring bar. Preventive maintenance (regular cleaning, conditioning with neutral creams, rotation with a second strap) extends useful life. Casati Milano provides an 18-month guarantee and can arrange repairs or replacements if necessary.