HMK Men's Carbon Lace Boots (Black, Size 8) Snowmobile Boots, Snow Boots, Winter Boots, Protective This boot is Waterproof, Windproof, Breathable made with our XR Performance Gold Level Membrane. It contains 1200 grams of Thinsulate Insulation. It is comfort rated to -40 degrees C. Ergonomic comfort cuff relieves pressure on the calf Rubberized lower for increased mobility Gusseted ankle flex for optimal mobility