Strap for Spirit Chronograph Flyback 39.5 Stainless Steel / Black

The lug width of the Longines Spirit L3.721.4.53.2 is 20 mm. This measurement represents the distance between the two attachment pins on the case and determines strap compatibility. Accurate measurement is essential: place a ruler between the pin holes and verify the distance is exactly 20 mm to ensure a perfect fit for your buckle or deployante.

The choice depends on your intended use and aesthetic preferences. For a classic, refined look, we recommend alligator in vegetable tanning (develops natural patina over time) or shell cordovan (exceptional durability and visual depth). For a modern compromise, regenerated calf leather offers uniform grain and moisture resistance. For intense sporting use, premium NATO in regenerated nylon is the most resilient and low-maintenance option. Match the strap colour to your dial (military blue with sand, black with dark brown, white with cognac) to enhance visual harmony.

Remove the strap by extracting the spring bars that connect it to the case. Use a dedicated spring bar remover tool or a small flat lever: position it under the pin and press gently upward to release the internal spring. Remove the old strap, align the holes of the new strap, and reinsert the spring bars until you hear a clicking sound. Verify that the buckle is properly oriented and the strap is securely attached before wearing your watch.

Yes, absolutely. Custom-made 20 mm straps are fully compatible with the Spirit L3.721.4.53.2 and offer significant advantages over factory straps: selection of premium leathers (alligator, shell cordovan, calf), choice of colour and finish, length adjustment, addition of initials or coloured stitching. Casati Milano's atelier crafts custom straps with rigorous tolerances and 18-month warranty, transforming your Spirit into a unique piece that reflects your personal taste.

Durability varies based on material, use, and maintenance. Vegetable-tanned alligator, if worn regularly but not daily, can last 3–5 years in good condition; shell cordovan, thanks to its dense grain, easily reaches 5–7 years. Regenerated calf leather offers average durability of 2–4 years. Essential maintenance—periodic cleaning, drying after water exposure, storage away from heat and direct sunlight—significantly extends lifespan. Quality artisanal straps like those from Casati Milano age gracefully, developing a natural patina that enhances aesthetic appeal over time.