Rolex
Datejust 31 178159-0020— lug 16mm

The Rolex Datejust 31 ref. 178159-0020 has a lug width of 16 mm. This measurement is taken as the internal distance between the two lugs of the case and determines the correct strap width. A 16 mm lug-width strap typically tapers to 14 mm at the keeper and buckle end.

For an 18-carat white gold case, a vegetable-tanned alligator strap is the most coherent artisanal choice: the natural scale grain echoes the texture of the fluted bezel. Alternatively, box calf leather or shell cordovan offer a denser, more durable surface. A white gold or silver PVD deployant clasp completes the pairing while maintaining chromatic consistency with the case.

The strap on the Rolex Datejust 31 is secured by spring bars with a diameter of 1.5 mm, fitted into the case lugs. Removal requires a dedicated spring bar tool — either a fork-tip or a push-pin type — to release the bars without scratching the white gold lugs. It is advisable to work on a soft surface and, if in doubt, to entrust the operation to a watchmaker or the Casati Milano atelier.

Yes. Any strap with a 16 mm lug width and standard spring bars is technically compatible with the Datejust 31 ref. 178159-0020. Milano Straps offers handcrafted straps in alligator, calf leather, shell cordovan and rubber, made to measure for this specific lug width. It is important to verify that the end-piece curvature matches the case profile for a precise fit.

The lifespan of a leather strap depends on the material, tanning method and frequency of use. A quality vegetable-tanned alligator strap, with regular conditioning and rotation with other straps, retains its structural and aesthetic integrity for 3 to 5 years of daily wear. Shell cordovan, owing to its dense fibre structure, can exceed 5 years. Milano Straps straps carry an 18-month guarantee against manufacturing defects.