The high back heel ensures for good insulation and if neccessary the EVA-foam inner sole is replaceable. The outer sole is made of slip-proof, environmentally friendly TPU. Even with gloves, the Bivy Booty by EXPED can be easily operated with one hand.Waterproof overshoe for all EXPED booties,One-hand operation even with gloves,High back heel for good insulation,EVA-foam inner sole is replaceable,Slip-proof, environmentally friendly TPU outer sole