The Bivy Booty from Exped is the waterproof, breathable shoe cover for all Exped Booties. The ultimate overshoe for basecamp, winter camping or just walking around camp in the woods. The durable sole is made of environmentally friendly TPU material and pulled up high around the sides as protection against ice, sharp edges and twigs. The padded heel is made of the same durable EVA foam of the inner sole and insulates when legs are stretched out on cold ground. Two adjustable elastic cords can be handled easily even with gloves to cinch the Bivy Booty tight. All seams are factory taped and the 3 layer outer shell(Exped VentAir®) is highly vapor permeable. The outer sole is of environmentally friendly TPU material, should be stored dry. The removable inner EVA sole can be replaced if necessary. "these boots are made for camp-walking...!"