Fleece lining Stretch-fit topline binding snugs calf to keep warmth in & cold out 5mm CR flex-foam bootie with four-way stretch nylon, 100% waterproof, lightweight & flexible 2mm thermal foam underlay added to the instep area for additional warmth EVA molded midsole with contoured footbed (internal) MS-1 molded outsole is rugged, aggressive & durable for maximum protection & stability