STABIL is a firm orthotic insert that holds and lifts the strained back of the heel. Relieves the Achilles tendon. Can also be used in only one shoe to equalize legs with uneven lengths (at the back of the heel: 7.5mm in size Medium and 9.5mm in size Extra Large). Can be used to lift the heel so it does not rub against the shoe. Made of fine vegetable tanned leather and is self adhesive.