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

The lug width of the IWC Pilot IW3713-31 is 21 millimetres. This measurement is taken by placing a ruler between the two lugs, parallel to the case, and measuring the internal clearance precisely. A strap must be exactly 21 millimetres wide to fit securely within the lugs without play or excessive tension.

For the Pilot IW3713-31, we recommend alligator as the premier choice, offering refined elegance and a regular grain that harmonises with the watch's minimalist aesthetic. Shell cordovan represents the artisanal alternative, developing an enchanting patina over time. Vegetable-tanned calf leather ensures initial suppleness and anatomical adaptation. NATO straps echo the watch's aviation heritage, whilst rubber is ideal for extreme conditions. Your choice depends on intended use and wearing context.

Strap replacement on the Pilot IW3713-31 is accomplished by removing the spring bars using a dedicated spring bar remover tool. Position the tool between the lug and case, compress the internal spring mechanism, and slide the bar free. Repeat for both sides. Insert the new strap by threading one end of the bar into a slot first, then relax the strap whilst inserting the opposite end. Operate with care to avoid scratching the case.

Yes, any strap manufactured with a 21-millimetre lug width is compatible with the IWC Pilot IW3713-31. High-quality aftermarket straps in alligator, shell cordovan, or calf leather fit the lugs perfectly without modification. Ensure the vendor explicitly specifies 21mm lug width, as straps of differing widths will not seat correctly in the lugs.

Leather strap longevity depends on material choice, frequency of wear, and climatic exposure. Artisan-grade alligator and shell cordovan last 5–8 years with daily use and proper maintenance. Calf leather, being more delicate, typically endures 3–5 years. Natural or synthetic rubber resists deterioration for 7–10 years in extreme conditions. The patina that develops is not degradation but natural aesthetic enrichment.