Kamik Men's Blackjack 2015 Black Boot 12 D (M) Leather Waterproof leather and nylon upper. Waterproof and flexible synthetic rubber shell. Seam-sealed waterproof construction keeps out the wet elements for a dry foot environment. Fixed 200B 3M Thinsulate insulation provides protective warmth against the cold. Moisture-wicking brushed nylon lining for excellent breathability. Padded collar and waterproof gusset tongue. Traditional lacing system with rustproof metal eyelets. Removable Kamik comfort antibacterial footbed offers both comfort and an odor-free environment. DEFENDER synthetic rubber winter outsole provides excellent traction. Temperature rating: -40F/-40C. (Yup, those conversion temps are correct!)