Strap for Speedmaster Moonwatch Co-Axial Split-Seconds Stainless Steel / Grey / Bracelet

The lug width of the Speedmaster (Non-Moonwatch) 311.30.44.51.01.001 is 21mm. This measurement is specific to the model and represents the internal distance between the two lugs of the case. It is essential to verify strap compatibility before purchase, as even differences of 1mm (20mm or 22mm) can cause imprecise fit or defective insertion.

For this 44.25mm chronograph, recommended materials are: alligator in dark shades (black, navy blue) to elegantly contrast with the brushed steel; vegetable-tanned calf leather for those who prefer natural patina and tactile grain; rubber or sport silicone for those who value chronographic functionality. Alligator remains the most elegant choice, while rubber maximizes versatility during water sports or timed activities.

The strap is removed using a spring bar tool: insert the flat tip under the inner lug from the shorter side of the lug, exert downward pressure to release the spring, then extract the bar itself. Repeat from the other side of the case. To install the new 21mm strap, align the spring bar and push until the click closes. If you are not experienced, the Casati Milano atelier performs the change expertly by appointment.

Yes, any strap with a 21mm lug width is theoretically compatible. However, to fully enhance a chronograph of this caliber, we recommend Italian artisanal leather with finishes consistent with the sportiness of the piece: brushed steel requires opaque or slightly brushed materials, not glossy ones. The customizable 21mm straps from MilanoStraps are built to this standard, with the option to choose leather, embroidered initials, and an 18-month warranty.

A quality leather strap (alligator, calf, shell cordovan) on a watch worn 5-6 days weekly lasts on average 3-4 years before requiring replacement. Wear factors: frequent moisture, direct sun exposure, and wrist pressure shorten durability. If you care for the strap carefully (quick drying after water, protection from heat), the patina improves over time and the piece can last over 5 years. Regeneration services (offered by Casati Milano) further extend the strap's life.