Strap for Horological Machine N°9 HM9 Flow Air Edition

The HM90 features a proprietary lug system integrated into the case design, not a standard lug arrangement. A conventional strap is incompatible. However, the bespoke workshop <a href="/pages/casati-booking">Casati Milano</a> creates fully custom straps built directly onto your watch, allowing you to enjoy artisanal leather without compromise.

During an in-studio appointment, our craftsmen precisely measure the proprietary lugs on your case, calculate the required strap dimensions, and collaborate with you on leather selection and finishing details. The strap is then hand-constructed and mounted directly to your timepiece, creating a seamless integration.

Deep-grain leathers – natural alligator, crocodile with visible spine scales, or vegetable-tanned calf – work best, as they maintain visual equilibrium with the case's complex geometry in titanium. Neutral tones – black, chocolate brown, slate grey – allow the watch's design to remain the star, while the leather's patina will develop in parallel to the case.

A strap constructed from premium leather and reinforced with hand-stitching typically lasts 5–7 years with regular wear, or considerably longer with proper care. The leather will age and develop patina much as the titanium case does, becoming an integral part of your watch's story.

The MB&F Horological Machines 90.TL.AB was conceived as an integrated architectural whole: its lugs are part of the case geometry and contribute to the overall volumetric harmony. This reflects Büsser's design philosophy of never separating form from function – every element is intentional and visible.