The 'Function' insole is no ordinary arch support. The secret to the support and comfort is the patented geometric groove and bubble, combined with the very specific cradling shapes and heel cup. The deep and specific shape of the heel cup is like a support seat for your heel and mid-foot. The deep heal stabiliser enables the insole shape to become narrower with every step. This creates more foot stability and neutral alignment. and also maintains the shape and shock absorbing function of the natural cushioning tissue under the heel bone. The deeper heel cup prevents the heel's protective tissue from spreading and exposing the heel bone to injury. The heel cup also resists the arch's tendency to over adapt and pronate.