Climbing skins are strips that attach to the bottom of Nordic, alpine touring or randonnée skis to help while ascending backcountry slopes. They are designed to be removed for skiing downhill. They are typically attached to the skis via a loop on the ski tip, a hook on the tail, and adhesive on the base of the skin. They are called skins because they resemble sealskin, from which the first ski skins were made.[1] They are typically made from nylon or mohair or a combination thereof, and are designed to let the ski slide forward on snow but not backward.[2][3] They are usually narrower than the ski to allow the ski edges to get a grip. Some ski resorts permit skinning.[4][5]