Jaeger-LeCoultre
Master Ultra Thin 1303501— lug 20mm

The lug width of the Jaeger-LeCoultre Master Ultra Thin reference 1303501 is 20mm. This measurement is taken with a caliper positioned between the inner walls of the two lugs on the 39mm white gold case.

For a white gold case with perpetual calendar, a smooth alligator strap — Mississippiensis or Hornback in polished finish — is the most appropriate choice given the watch's formal character. Smooth box-calf leather is an alternative for elevated daily wear, developing a personal patina over time that complements the dial's restraint.

Strap replacement is accomplished using standard 20mm spring bars housed between the case lugs. With a dedicated lever tool or thin flathead screwdriver, you can remove the spring bars without risking scratches to the white gold case. We recommend working on a soft surface and, if in doubt, consulting a watchmaker or the Casati Milano service.

Yes. Any aftermarket strap with a 20mm lug width and taper consistent with the Master Ultra Thin's curved lugs is compatible. On milanostraps.it you will find artisanal straps in alligator, calf leather, and other materials specifically selected for 20mm lugs, with the option for bespoke customization through Casati Milano.

A leather strap's lifespan depends on leather quality, frequency of use, and exposure to perspiration and weather. A quality alligator or calf strap, with alternating wear and proper maintenance, can last 2 to 5 years while retaining structural and aesthetic integrity. Casati Milano straps are covered by an 18-month warranty against manufacturing defects.