Osprey Adult Neoprene Wetsuit Boot 5mm Made of 5 mm neoprene, these boots are extremely flexible and keep in the heat. Featuring great grip on a slippery surfaces, these Wetsuit Boots are equipped with a non-slip sole, and this model also has a reinforced toe and heel. Flexible 5mm Neoprene with Nylon Reinforced toe and heel for extra protection and Velcro adjuster Non-slip sole