Every strap we build is made from durable Italian calfskin with exceptionally fine grain that are vegetable-tanned, meaning the leather has been tanned in the old-fashioned way using organic tannins from tree bark. Vegetable-tanned leather matures without ruining and it is non-sensitive. Because our leather is made of natural materials and tannings, your strap will develop a beautiful patina and over time will develop in colour with use.