Strap for Master Collection 40 Chronograph Calendar Stainless Steel / Black / Strap

The lug width of the Longines Master Collection L2.673.4.51.5 is 21mm. This non-standard measurement represents a deliberate design choice by the manufacture and corresponds to the horizontal space between the spring bars. To verify compatibility, measure the space between the pins with a digital calliper: if you obtain 21mm, the strap is compatible. Do not confuse this measurement with the total length of the strap or the width of the buckle.

The best strap depends on your intended use. For formal or business wear, we recommend alligator or vegetable-tanned calf leather in black or burgundy tones, paired with an integrated deployante clasp. For daily use, fine-grained calf leather offers superior resistance to surface scratches. For marine or sporting environments, consider vulcanised rubber or technical fabric straps. The Master Collection particularly complements shell cordovan, which develops a golden patina over time through contact with the skin's natural oils.

To change the strap, obtain a dedicated spring bar tool. Insert the flat lever of the tool into the gap between the spring bar housing and the case, pushing inward until the pin is released from its seat. Remove the old strap. Insert the new strap by aligning the holes with the pins, then use the tool to reposition the pins into their housings, ensuring they are fully locked. Verify that the strap sits symmetrically relative to the case before wearing the watch.

Yes, provided the aftermarket strap has a 21mm lug width. Many standard straps (18, 20, 22mm) are not compatible, since 21mm is a non-standard measurement. Bespoke leather straps allow you to adapt the total length to your wrist and freely choose materials, colours and finishes. Always verify compatibility by measuring the space between the spring bars before ordering.

The lifespan of a leather strap depends on frequency of use, the material chosen, and environmental conditions. High-quality alligator or vegetable-tanned calf leather can last 3–5 years of daily wear before requiring replacement. Shell cordovan, owing to its density, can extend to 6–7 years. Prolonged exposure to sunlight, salt water and humidity accelerates wear. Regular maintenance (cleaning and conditioning with specific creams) significantly extends the strap's useful life.