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

The lug width of reference 231.20.34.20.55.001 is 18 mm. This measurement is specific to this generation of Aqua Terra and requires straps calibrated to 18 mm to avoid excessive play between the case lugs. Before purchasing, verify your exact measurement with a digital caliper, measuring from the inner left lug shoulder to the inner right lug shoulder.

To enhance the iridescent mother-of-pearl and Sedna rose gold, Nile crocodile in charcoal or taupe tones is the most balanced choice: the regular grain texture creates aesthetic continuity without competing with the dial. Alternatively, vegetable-tanned calf offers a softer surface, while burgundy shell cordovan adds refinement for those who do not wear the watch in humid environments.

To change the strap, you need a springbar tool (a small tool with a bifid tip) and a clean work surface. Use the springbar tool to gently compress the elastic pin of the lug; as soon as the pin retracts, slide the old strap outward. Repeat for the opposite lug. To install the new strap, align the internal hole with the elastic pin, press gently until you hear the click of engagement, and verify that both lug shoulders are fully inserted.

All straps with 18 mm lug width are compatible with this model, regardless of material (crocodile, calf, NATO, rubber, shell cordovan). Always verify that the strap is not too thick (beyond 4.5 mm) in the transition zone with the lug, otherwise it may become stuck between the case and the attachment. Milano Straps offers 18 mm compatible straps, customizable in leather, sizes and colors.

Durability depends on the material and contact with water. Crocodile, if kept dry, lasts 4-6 years of daily use. Vegetable-tanned calf, being more porous, lasts 2-4 years. Shell cordovan, if regularly maintained (monthly brushing, quarterly conditioning), can reach 7-10 years or more. Elastomer (FKM rubber) resists up to 5-8 years in conditions of sun and salt water exposure. Avoid wearing the leather strap during diving or pool activities to extend its life.