Strap for Master Collection 40 Moonphase Stainless Steel / Blue-Diamond / Bracelet

The lug width of the Longines Master Collection L2.909.4.97.6 is 21 mm. This is the precise distance between the lugs on either side of the case. To verify this measurement, place a ruler parallel to the case, measuring from lug to lug. It is critical to confirm this measurement before purchasing an aftermarket strap, as even 1 mm variations will compromise fit.

The optimal choice depends on intended wear. For formal elegance, black or dark brown alligator enhances the dial's minimalism and evokes classical watchmaking heritage. For refined daily wear, calf leather with vegetable tanning in medium brown offers softness and develops patina over time. For those seeking a strap destined to age nobly, shell cordovan in brandy or black is the definitive choice. If absolute practicality is your priority, a heavyweight canvas or vulcanised rubber NATO reduces the Master to pure instrument without compromise.

Strap replacement requires basic tools: a spring bar tool and a protected work surface. Position the watch on its side, locate the hole in the spring tension mechanism of the lug, gently insert the tool to compress the spring, then withdraw the pin. Repeat on the opposite side. Once both pins are removed, extract the previous strap and insert the new one, ensuring the pins lock securely on both sides. If you lack experience, a professional watchmaker ensures safety and avoids potential case damage.

Yes, provided the strap is manufactured for 21 mm lug width. Many artisanal strap producers offer compatible solutions using materials superior to original equipment. Verify that the strap is fitted with pins or passants capable of accommodating the original 1.8 mm diameter Longines pins. Custom-built straps additionally permit personalisation of total length, colour, and buckle type according to your preferences.

The lifespan of a leather strap depends on intensity of wear and material quality. An alligator or vegetable-tanned calf strap, worn daily, maintains structural integrity for 3–5 years, after which it typically shows wear in the keeper and stitching. Shell cordovan, due to fibre density, can endure 5–7 years of regular use. Determining factors include exposure to water and perspiration, cleaning frequency, and rest periods between wears (ideally alternating two straps for the same watch). A well-maintained strap, treated periodically with protective wax and stored in dry environments, significantly extends operational lifespan.