Strap for Seamaster Aqua Terra 150M Co-Axial 41.5 Stainless Steel / Red Gold / Grey / Bracelet

The lug width of the 231.20.42.21.06.002 model is 20 mm. This measurement is critical for strap compatibility: it is measured perpendicularly between the case lugs at the point where the barrel pins attach, not at the lateral slots. The lug depth is approximately 5.5 mm, so the ideal strap should not exceed 3.5 mm in thickness.

For the two-tone Red Gold and steel Aqua Terra 231.20.42.21.06.002, we recommend alligator leather with vegetable tanning in cognac or warm brown tones to enhance the rose gold, or an elegant calf leather in deep black for a formal style. For summer, a dark FKM rubber or NATO fabric maintains the sporty character. The choice depends on usage environment and personal aesthetic preferences.

Strap replacement requires the use of a spring bar tool to remove the barrel pins (the small pins that support the strap) from the case lugs. Position the tool in the spring bar groove, lift slightly to unlock, then remove the old strap. Install the new strap by aligning the holes with the barrel pins and pressing until it clicks into place. Verify that the strap is securely positioned before wearing the watch.

Yes, any strap with a 20 mm lug width is compatible with the 231.20.42.21.06.002. However, ensure that the strap thickness does not exceed 3.5 mm to avoid friction or misalignment in the lugs. Artisanal straps with vegetable tanning offer superior construction quality compared to standard straps, developing a natural patina that pairs perfectly with the noble materials of the two-tone case.

The lifespan of a leather strap depends on usage intensity and tanning quality. A high-quality alligator or calf leather, subjected to moderate daily use (not constantly exposed to water or excessive sweat), maintains structural integrity for 2-3 years. With regular maintenance (gentle cleaning, avoiding prolonged wetting) the lifespan extends. Artisanal straps with vegetable tanning age gracefully, developing characteristic patina even after 5-7 years of intense use. The warranty on custom Casati Milano straps is 18 months against manufacturing defects.