Strap for Seamaster Aqua Terra 150M Co-Axial 38.5 Stainless Steel / Red Gold / Black / Bracelet

The lug width of the 231.20.39.21.51.003 is 20 millimetres, measured from the inside of the lower hole to the inside of the upper hole. This dimension does not correspond to the most common standards (18 or 22 mm), therefore it is essential to verify the width before ordering an aftermarket strap to avoid incompatibility.

The choice depends on the intended use. For formal contexts, vegetable-tanned alligator or napped calf offer elegance and patina that develops over time. For a more sporty aesthetic, shell cordovan guarantees exceptional durability and a refined patina. NATO straps or FKM rubber are ideal if you want to emphasize the technical and diving character of the watch.

Remove the old strap by unscrewing the lug pins using a dedicated tool (spring bar remover). Once the pins are extracted, the case remains free from the strap. Insert the new strap by aligning the holes and reintroduce the pins, screwing them until the case adheres completely. Do not overtighten to avoid damaging the threading.

Yes, any strap with a 20mm lug width is dimensionally compatible. However, we recommend verifying that the strap holes are perfectly aligned with the case attachment holes. Straps handcrafted by specialized ateliers such as Casati Milano guarantee precise tolerances and superior quality materials.

The lifespan of a leather strap varies based on the material and usage. A high-quality handcrafted vegetable-tanned strap lasts on average 3-5 years with daily use. Shell cordovan, thanks to its superior density, can reach 7-10 years. Humidity, sweat and constant sun exposure reduce longevity. Straps made of rubber or NATO have similar lifespans but less perceived aesthetic degradation.