Strap for Constellation Co-Axial 31 Stainless Steel / Yellow Gold Claws / MOP

The lug width is 18mm. This measurement is specific to the 31mm case and represents the result of classical proportions calculated by Omega. Measuring correctly means positioning the digital caliper between the two case shoulders, at the point where the strap attaches. Never confuse lug width with case diameter.

Alligator is the natural choice for this dress case. An alligator with vegetable tanning develops a patina over time that resonates with the aging of yellow gold. Valid alternatives are full-thickness English calf for a more casual tone, or dark shell cordovan for those seeking an artisanal emotional charge. Absolutely avoid canvas, rubber, and fabric or NATO straps, which betray the dress spirit of the model.

Strap replacement requires removal of the spring bars. Obtain a spring bar tool, position it under the bar on the opposite side from where you want to extract the strap. Press gently downward until the bar compresses, then remove the old strap. Insert the new strap by aligning the holes, then snap the bar into the resting position. For a dress case like this, it is advisable to have the operation performed by a watchmaker to avoid scratches on the case.

Yes, provided the lug width is exactly 18mm. Always verify this specification before purchase. Standard 18mm straps are fully compatible with the 123.20.31.20.55.004. Consult our 18mm strap catalog to choose the material, color, and deployant ideal for your watch.

Durability depends on use, leather quality, and tanning method. A quality alligator or calf with vegetable tanning offers a lifespan of 4-6 years with moderate daily wear. Shell cordovan, more resistant, reaches 6-8 years. Wear is natural and desirable: the patina that develops enriches the strap. Casati Milano custom straps include an 18-month warranty against manufacturing defects and variations due to irregular tanning.