Strap for Pilot's Watch Spitfire Double Chronograph Stainless Steel / Black / French / Bracelet

The lug width (ansa in Italian) of the IWC Pilot IW3713-39 is 21mm. This is the critical measurement for selecting a compatible strap. Measurement is taken between the inner pins of the case using a digital calliper or by consulting official IWC specifications.

The best strap choice depends on intended use and aesthetic preference. For the aviator heritage reference, a strap in vegetable-tanned Tuscan leather or Barenia preserves the model's historical identity and develops patina over time. For sports applications and durability, a ripstop NATO strap is ideal. Alligator represents a more formal option, suitable for elegant occasions.

Strap replacement is accomplished via spring bars that secure the strap to the case lugs. Obtain a spring bar remover tool, which allows access to the release mechanism without damaging the case. Gently push the spring towards the centre to extract the pin, then align the new strap with the lugs and ensure the spring clicks into position. The operation takes minutes and requires no technical expertise.

Yes, quality aftermarket straps with a 21mm lug width are fully compatible. Compatibility is guaranteed by standardisation of lug width and pin diameter. Premium straps crafted by experienced artisans such as those offered by MilanoStraps and Casati Milano often exceed original strap durability and finish quality, owing to attention to constructive detail and material selection.

A natural leather strap subjected to vegetable tanning, when maintained correctly (protection from excessive moisture, ambient-temperature drying, periodic conditioning), has an estimated lifespan of 3-5 years under daily use. Climate, physical activity and sun exposure affect ageing speed. Tuscan and Barenia leathers develop patina which, although altered, maintains strap structural integrity beyond 5 years. MilanoStraps offers an 18-month warranty on custom Casati Milano straps.