Tyrolia PRW 12 GW PowerRail snow ski bindingsPowerail model designed to work on wider skis. Wider toe rest transmits energy to the edges of wider skis Soft entry twin cam heel Diagonal heel offers forward release in a 45 degree diagonal direction to both sides Full diagonal toe offers 180 degree release in backward direction Fits both Grip Walk and Alpine sole boots. THIS BINDING REQUIRES POWER RAILS MOUNTED TO THE SKI that are not included. If you are buying this binding to install on a ski