VERSATILE TRACTION: Customized traction on the fly; easily change soles as conditions or terrain demand. WATERPROOF: 100% Waterproof breathable bootie construction combined with waterproof leather keeps feet bone dry. INSULATION: 600g of 3M Thinsulate insulation, highly rated for extreme winter cold. DURABILITY: Molded TPU toe cap for durability and protection with recessed stitching for added abrasion resistance. FIT SYSTEM: Boa M4 Fit System for fast and effortless on/off and custom fit. TEMP RATING: Comfort rated down to -40 Degrees Fahrenheit.