Strap for Seamaster Aqua Terra 150M Co-Axial 38.5 Annual Calendar Stainless Steel / Blue

The lug width is 20mm. This measurement is specific to this model: measured between the lateral lugs of the case, the usable space for the strap is exactly 20mm. It is not compatible with 22mm straps (larger Seamaster sizes) or 18mm. You can verify this by placing a ruler between the two lugs: you will find this precise dimension.

For this model, vegetable-tanned alligator is the most elegant choice: the leather texture pairs perfectly with the Teak Concept dial and creates a bespoke timepiece. A sophisticated alternative is full-grain calf leather, which develops a natural patina over time. For those who prefer functionality, shell cordovan resists wear better. In sports contexts, a fine-weave NATO strap maintains the style while ensuring practicality.

The change is straightforward: use a spring bar tool (thin lever tool) to gently push the pin that holds the strap to the lugs. Remove the old strap and insert the new one by snapping the pin into the lateral slots of the case. It is important that the strap is exactly 20mm in width, otherwise it will not fit correctly. If you are unsure, contact a trusted watchmaker: the service costs only a few euros and ensures that no damage is done to the case lugs.

Yes, any strap with a 20mm lug width is compatible with the 231.13.39.22.03.001. Artisanal straps from Milano Straps are built to these specifications and allow customization in leather (alligator, calf, shell cordovan), embroidered initials and choice of buckle or deployant. The Casati Milano atelier can also create bespoke straps chosen directly by you in consultation via WhatsApp.

A quality leather strap, with vegetable tanning and artisanal craftsmanship, lasts on average 4-6 years if subjected to moderate daily use. Durability depends on frequency of wear, humidity and wrist perspiration. A titanium deployant with internal synthetic protection extends the life by 2-3 years, as it isolates the leather from direct perspiration. With minimal maintenance (occasional cleaning with a damp cloth, storage in dry environments), the strap maintains structural integrity longer. Casati Milano provides an 18-month warranty on all straps made.