Strap for Datejust 31 Stainless Steel Domed / Oyster / Blue Roman

The lug width of the Rolex Datejust 31 reference 178240-0036 is 16mm. This measurement is taken between the two lugs on the inner side of the case, parallel to the bezel, using a vernier calliper. It is a non-standard size that requires straps specifically produced for this dimension.

For the Datejust 31 in stainless steel at 31mm, the most suitable materials are belly-cut alligator for formal occasions, vegetable-tanned calfskin for daily wear with natural patina development, and shell cordovan for superior longevity and a compact surface. In sporting contexts, vulcanised rubber or nylon NATO straps are the most practical alternatives. The 16mm lug width requires bespoke production or selection from dedicated ranges for this size.

To replace the strap on the Datejust 31 178240-0036, a fine-tipped spring bar tool is required. Insert the tip into the lug groove, compress the spring bar and slide the strap free from the lug. Care must be taken to avoid scratching the OYSTERSTEEL case. Alternatively, a watchmaker or the Casati Milano atelier can carry out the replacement in a matter of minutes during a fitting appointment.

Yes. The aftermarket offers compatible straps for the Datejust 31 178240-0036, though the 16mm lug width restricts availability compared to the more common 18mm and 20mm sizes. Milanostraps.it produces and curates straps calibrated specifically for the 16mm lug, available in a range of materials and finishes. The Casati Milano atelier also offers fully bespoke straps with individual selection of leather, colour, stitching and clasp.

The lifespan of a leather strap on a Rolex Datejust 31 depends on the material and daily care. A vegetable-tanned calfskin strap, well maintained, typically lasts 2–4 years with daily use. Shell cordovan, owing to its dense fibrous structure, can exceed 5 years. Quality alligator, treated with protective wax and kept away from prolonged moisture, has a comparable lifespan. Casati Milano's 18-month guarantee on manufacturing defects covers the quality of the handcrafted work.