Strap for Horological Machine N°4 HM4 Thunderbolt

The MB&F Horological Machines 40.TSL.B features a lug width of 20mm. This measurement represents the internal distance between the two lug shoulders on the case. For compatibility assurance, measure this distance precisely before ordering your bespoke strap.

Given the 54mm titanium case, we recommend straps in vegetable-tanned alligator, vintage calf leather, or shell cordovan. For daily wear, NATO and FKM rubber offer superior durability. Antique grey alligator with warm stitching dialogues elegantly with satin titanium; polished black calf offers restraint; royal blue or graphite grey NATO provides summer versatility.

Strap replacement occurs via the spring bar, located inside the lug. Use a dedicated two-prong tool to compress the spring on one side, extracting the bar delicately. Position the new strap by inserting the bar into the opposite seat, then release the spring. Proceed with caution to avoid scratching the satin titanium case finish.

Yes, you may fit aftermarket straps of quality provided they respect the 20mm lug width specification. The bespoke leather, NATO, and rubber straps from milanostraps.it are fully compatible with your timepiece. Always verify that the spring bar thickness corresponds to your lugs to ensure secure fastening.

A quality bespoke leather strap with vegetable tanning lasts approximately 3–5 years of daily wear, depending on UV exposure, humidity, and wearing frequency. Alligator and shell cordovan age nobly. Regular maintenance with specific balms and rotation with alternative straps substantially extends the longevity of the piece.