Strap for Navitimer 8 B35 Automatic Unitime 43 Stainless Steel / Black / Black Croco / Pin

The lug width of the Breitling AVI AB3521U41B1P1 is 23 mm. This non-standard measurement — departing from the more common 20–22 mm range — reflects a deliberate design decision rooted in the AVI family's aviation heritage. When replacing the strap, it is essential to use one specifically sized at 23 mm to ensure a precise, play-free fit between the lugs.

The materials most consistent with the Breitling AVI AB3521U41B1P1's design DNA are: Mississippi-grain alligator in midnight blue or tobacco for formal wear, shell cordovan for those seeking a natural patina over time, ballistic nylon NATO to honour the model's aeronautical spirit, and vulcanised rubber for sporting use. The final choice depends on the colour of the dial and the intended occasion.

The strap on the Breitling AVI AB3521U41B1P1 is replaced using a double-tipped springbar tool. Gently lever the springbars housed within the 23 mm lugs, taking care not to scratch the stainless steel case. It is advisable to work on a soft surface and, if inexperienced, to entrust the operation to a watchmaker or to the Casati Milano atelier.

Yes, high-quality aftermarket straps compatible with the Breitling AVI AB3521U41B1P1 are available. Milano Straps offers a range of 23 mm hand-crafted Italian straps in various materials and finishes. For a fully bespoke result with personal leather selection, the Casati Milano service is available by appointment. All straps are fitted with standard 23 mm springbars.

The lifespan of a leather strap depends on the material, care routine, and frequency of wear. A quality alligator strap, regularly conditioned and rotated with other straps, can last between three and six years whilst retaining its aesthetic integrity. Shell cordovan, owing to the density of its fibre, tends to last longer and develops a progressive patina. Milano Straps provides an 18-month guarantee against manufacturing defects on all its straps.