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: 1200g 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. COMFORT: Premium aerogel frost barrier footbed. TEMP RATING: Comfort rated down to -60 Degrees Fahrenheit.