Muck Boot Men's Arctic Sport Boots - The Breathable Airmesh(TM) lining ensures comfort in any temperature. The boot fits snug around your lower leg to hold warmth in and keep the cold out. The outsole is rugged, aggressive, and durable. Your comfort is increased by the EVA molded midsole with contoured footbed. The boots are 100% waterproof for your protection and comfort. All the standard MUCK BOOT features plus: Stretch-fit topline binding snugs leg to keep warmth in and cold out 5mm CR flex-foam bootie with four-way stretch nylon, 100% waterproof, lightweight and flexible MS-1 molded outsole is rugged, aggressive and durable for maximum protection and stability Double reinforcements on the instep, heel and Achilles areas 2mm thermal foam underlay added to the instep area for additional warmth EVA molded midsole with contoured footbed Reinforced toe Added toe protection with a wrap-up bumper Comfort range of -40 degrees F to 60 degrees F