Rolex
Datejust 31 178341-0006— lug 16mm

The Rolex Datejust 31 ref. 178341-0006 has a lug width of 16mm. This measurement is taken internally between the two lugs using a millimetre calliper positioned perpendicular to the case axis. It is the defining specification for aftermarket and bespoke strap compatibility.

For the Datejust 31 in steel and Everose gold, the most suitable straps are square-grain or round-grain alligator for formal elegance, vegetable-tanned calf leather for everyday versatility and natural patina development, or shell cordovan for a structured, compact profile. A deployant clasp in steel or rose gold extends strap longevity and complements the two-tone case aesthetically.

Strap replacement requires a fine-tipped spring bar tool to remove the spring bars from the lug holes. The Datejust 31 lugs have a curved profile: it is advisable to use a dual-tip tool and work with the caseback resting on a soft surface to avoid scratching. Alternatively, Casati Milano offers a professional fitting service at the atelier by appointment.

Yes. Any strap with a 16mm attachment and curved or straight ends suited to the Datejust 31 profile is compatible. Milano Straps offers a curated selection of handcrafted 16mm straps in various materials and finishes, available bespoke or ready to ship, with no modification to the original case required.

Longevity depends on the material and conditions of use. A quality alligator strap with vegetable tanning and careful finishing typically lasts 2–4 years with daily wear, provided it is kept away from water, excessive perspiration, and direct heat. Shell cordovan, being denser and more resistant, can exceed 4–5 years. Using a deployant clasp significantly reduces stress on the buckle area and extends overall strap life.