The Sidi Caliper Buckle Strap is designed to replace used and worn straps. Replacement is dead simple. Simply slide the old straps out of the molded loop located on the instep closure band, then insert the new straps in the same loop. These straps only work with Sidi Caliper Buckles and will not function with any other Sidi buckle or other buckle systems. These are sold in pairs, so buy one to replace both buckles straps on one pair of shoes.