Rolex
Day-Date 36 118389-0085— lug 20mm

The lug width of the Rolex Day-Date 36 118389-0085 is 20 mm. This measurement represents the distance between the two spring bars that attach the strap to the case lugs and is the standard specification for all compatible straps for this model. Always verify this dimension before purchase, as even a 1 mm difference will compromise the fit and aesthetic appearance of the watch.

For the Day-Date 36 in white gold (reference 118389-0085), alligator leather remains the classical choice, as its natural texture highlights the metallic lustre of the precious metal. Calf leather is ideal for those preferring a smooth, understated grain, whilst FKM rubber is the contemporary solution for those who wear the watch in sporting or maritime contexts. Your choice depends on the intended use and personal aesthetic preference.

Strap replacement requires extraction of the spring bars from the lugs: use a spring bar tool (a specialised implement with two curved ends) to apply lateral pressure to the bar and release it from the case holes. Once removed, insert the new strap ensuring the spring bars are correctly seated in both lugs. If you lack experience, it is advisable to consult a watchmaker or Casati Milano to prevent damage to the case.

Yes, any strap with a 20 mm lug width is compatible with the Day-Date 36 118389-0085. The critical requirement is verifying that the strap is designed for 20 mm lugs and that construction quality matches the intrinsic value of the watch. Whilst Rolex provides original straps in white gold or leather, numerous artisanal manufacturers produce superior alternatives with personally curated materials.

The lifespan of a leather strap depends on material quality and usage patterns. High-grade alligator or calf leather, worked with traditional tanning techniques, will withstand 5–7 years of daily wear, extending to 10–12 years with occasional use. FKM rubber typically lasts longer (8–12 years) owing to its chemical and mechanical resilience. Regular maintenance—gentle cleaning and drying after moisture exposure—significantly extends strap longevity.