Strap for Spirit Automatic 40 Black / Strap

The lug width of the Longines Spirit L3.810.4.53.0 is 21mm. This measurement is determined by calculating the distance between the two lug pins on the case at the 12 o'clock and 6 o'clock positions. It is important to verify this measurement before purchasing an aftermarket strap, as 21mm is an intermediate dimension that does not correspond to universal standards such as 20mm or 22mm.

The ideal strap depends on intended use and personal aesthetic preferences. For formal elegance, we recommend natural alligator with traditional tanning, which develops a fascinating patina over time. For everyday versatility, vegetable-tanned calf leather offers comfort and durability. For a more technical and sporty style, a NATO strap in Cordura fabric maintains the avionic heritage of the model. Structured rubber is perfect for humid environments or dynamic activities.

Strap replacement requires a specific tool (spring bar tool). Position the watch with the caseback facing upward. Insert the flat tip of the tool into the lateral slots of the pin, exerting gentle downward pressure until the pin retracts. Remove the pin and take off the old strap. Insert the new strap into the pin position and ensure it locks correctly on both sides. If you prefer a risk-free approach, the Casati Milano atelier offers professional strap-changing services.

Yes, the model accepts aftermarket straps in any material with an exact 21mm lug width. milanostraps.it offers a complete collection of compatible straps in alligator, calf, shell cordovan, NATO, and rubber, all customisable in length, initials, and stitching thread choice. Compatibility is guaranteed by the precision of the lug width measurement.

The lifespan of a leather strap depends on the material, frequency of use, and maintenance. High-quality alligator with vegetable tanning can last 5-10 years with moderate use and occasional cleaning. European calf leather offers similar durability. Structured rubber provides superior resistance in humid environments, with a useful life of up to 8-12 years. The end of the strap (the adjustable part worn on the wrist) experiences greater wear: this is the critical point to monitor over time.