Strap for Master Collection 42 Chronograph Calendar Stainless Steel / Yellow Gold / Silver-Arabic / Bracelet

The lug width of the Longines Master Collection L2.773.5.78.7 is 20 mm. This measurement represents the internal distance between the two lateral lugs (or spring bars) of the case. To verify correctly, use a digital calliper to measure the internal space where the strap runs, without compressing the lugs. A 20 mm strap fits perfectly into the lug width, ensuring uniform tension distribution during wear.

The most suitable strap depends on intended use and desired aesthetic character. For maximum elegance, we recommend Nile alligator in dark shades (burgundy, brown, black), which enhances the two-tone gold-steel design. For a natural patina that evolves over time, shell cordovan represents the most refined choice. Smooth calf leather in grey or black offers a contemporary and versatile approach. For a more technical and sporty character, rubber or NATO fabric straps confer an instrumental quality to the chronograph. All materials must have a thickness consistent with the 42 mm case diameter.

Strap replacement requires removal of the spring bars that connect the strap to the lugs. Position your watch on a clean surface and use a dedicated spring bar removal tool, or consult a qualified watchmaker. After extracting the spring bars from the lug ends, the old strap separates easily. Insert the spring bars into the new 20 mm strap, ensuring the holes align perfectly with the lugs, then slide the spring bars until fully locked. To avoid the risk of scratching the case, contact a specialised atelier like Casati Milano, which offers strap change and customisation services.

Yes, a quality aftermarket strap of exactly 20 mm width is fully compatible with your L2.773.5.78.7 lugs, provided it respects the precise width and features robust construction. An aftermarket strap allows freedom of aesthetic expression and adapts the chronograph to different contexts (sporty, elegant, formal). Online you will find a selection of compatible 20 mm straps made in fine leather (alligator, calf, shell cordovan) with artisanal finishes. To ensure maximum quality and longevity, choose suppliers offering guarantees on materials and stitching.

The lifespan of a leather strap depends on material type, usage patterns and storage conditions. Fine-quality alligator or calf, worn daily, maintains structural integrity for 3–5 years before showing visible wear signs (thinning, micro-cracks along stitching). Shell cordovan, thanks to its superior density, can last 5–7 years. Rubber is notably more durable (7–10 years), while NATO fabric withstands 10 years with proper care. To extend strap life, avoid direct sunlight exposure, prolonged humidity and extreme temperatures. Hand-stitched construction using saddle stitch (as in specialised ateliers) significantly increases longevity compared to industrial stitching.