Stretch-fit topline binding snugs calf to keep warmth in and cold out; 5mm NEOPRENE bootie with four-way stretch nylon, 100% waterproof, lightweight and flexible; Extended rubber overlay for added protection; 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 and durable for maximum protection and stability