Strap for Spirit Automatic 40 Silver / Bracelet

The lug width of the Longines Spirit L3.810.4.73.6 is 21mm. This measurement, 1mm larger than the standard for many 40mm watches, was chosen by Longines for ergonomic reasons specific to the tonneau case design. To verify the measurement, measure the internal distance between the two horizontal lugs with a digital calliper.

Superior quality alligator is the ideal choice for the Spirit, as it emphasises the formal character of the watch and allows precise micro-adjustment thanks to elastic adjustment bars. Alternatively, vegetable-tanned calf offers greater versatility and develops natural patina over time, whilst FKM rubber remains the most robust solution for humid or sporting environments.

The Spirit uses straight spring bars. Remove the bar from the upper lug using a spring bar tool, lower the strap, then repeat from the lower lug. Insert the new strap aligning it with the lugs, thread the upper bar and ensure it is positioned centrally, then repeat with the lower lug. Verify that the strap is perfectly horizontal.

Yes, quality aftermarket straps for 21mm lugs exist, both ready-made and customisable. MilanoStraps offers a collection of compatible 21mm straps in various materials. For a fully personalised experience, the Casati Milano atelier creates bespoke artisan straps with choice of leather, live WhatsApp updates and 18-month warranty.

A quality leather strap (alligator or vegetable-tanned calf) typically lasts 4-7 years with moderate daily wear. Durability depends on sun exposure, ambient humidity and maintenance habits. An FKM rubber strap lasts 8-10 years whilst maintaining elastic properties, thanks to polymer chemical stability. The patina that develops does not affect structural integrity.