Muck Youth Arctic Sport - 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(TM) features plus:;Stretch-fit topline binding snugs calf to keep warmth in and cold out ;Fleece lining ;5mm CR flex-foam bootie with four-way stretch nylon, 100% waterproof, lightweight and flexible ;Durable, natural rubber shell ;Comfort range of sub-freezing conditions to 85