Comfort and warmth for the most extreme outdoor conditions. Fleece lining Stretch-fit topline binding snugs leg to keep warmth in and cold out 8mm Neoprene bootie with four-way stretch nylon, provides the ultimate in warmth, comfort, and waterproofing that you expect from a Muck Boot. 100% waterproof, lightweight and flexible 2mm thermal foam underlay added to the instep area for additional warmth EVA molded midsole cushions with every step MS-1 molded outsole is rugged, aggressive and durable for maximum protection and stability