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

The lug width (ansa measurement) of the Longines Master Collection L2.759.4.51.7 is exactly 20 millimetres. Measurement must be taken from inside to inside of the two lugs using a digital calliper. No tolerance exists: a strap measuring 19 or 21 millimetres will be mechanically incompatible.

For this stainless steel chronograph, alligator leather represents the ideal choice in terms of elegance and patina development over time. Vegetable-tanned calf leather offers an equivalent alternative with superior daily versatility. A high-quality canvas NATO strap constitutes the sports option, whilst synthetic rubber is recommended for casual contexts.

Strap replacement requires a specific tool called a spring bar punch. Insert the punch into the small lateral hole of each spring bar, applying gentle pressure to release the pin outward. Align the new strap with the lugs and re-insert the pins until they click into position. If uncertain, consulting a professional watchmaker is advisable.

Yes, provided the lug width is precisely 20 millimetres. High-quality aftermarket straps (alligatore, calf, canvas NATO) are completely compatible with this model and often offer broader aesthetic choices than original straps. Ensure your supplier maintains precise manufacturing tolerances.

A quality alligator or calf leather strap typically lasts 3 to 5 years of daily wear, depending on frequency of use and exposure to water and sunlight. Replacement is not a failure but a natural evolution: leather wears and accumulated patina makes a change an opportunity for aesthetic renewal. A canvas NATO, conversely, can last up to 10 years if kept dry.