Strap for Big Crown ProPilot Big Date E-Sling

The lug width of this model is 20 millimetres. This measurement is determined by measuring the internal distance between the pins that pass through the case lugs. It is the historical standard of Swiss military chronographs and is essential for selecting a compatible strap without sacrificing structural rigidity or proportional aesthetics.

Vegetable-tanned calf leather in grey or dark brown tones represents the ideal compromise. It develops a patina complementary to oxidised bronze, is sufficiently resistant to daily wear, and respectfully maintains the chronograph's aviation heritage. Greige alligator amplifies the theatrical quality of ageing further; black NATO offers tactical versatility and maximum practicality for professional environments.

Use a spring bar removal tool to extract the pins that connect the strap to the lugs. Position the tool tip in the small hole beneath the pin, apply gentle downward and lateral pressure to decompress the internal spring, then withdraw the pin. Repeat on both sides. Proceed in reverse order to install the new strap, ensuring the pins are fully inserted and click into position.

All straps equipped with lugs compatible with the 20-millimetre width are immediately compatible. This includes vegetable-tanned full-grain leather, alligator, exotic leather (cordovan, ostrich), woven NATO straps, FKM rubber and vulcanised natural rubber straps. Compatibility is guaranteed as long as the base width (which rests on the lug) corresponds to 20mm.

Low-quality calf leather typically fails after 18–24 months of daily wear; full-grain vegetable-tanned leather maintains functionality beyond 36–48 months. Alligator, being more fragile, degrades aesthetically after 24–36 months of regular use, though it may remain functional. Lifespan depends on: frequency of wear, exposure to humidity/perspiration, and preventive maintenance (cleaning, conditioning with beeswax). Users wearing the ProPilot in humid environments should consider NATO or rubber for superior longevity.