Design: 100% waterproof breathable bootie construction combined with waterproof leather 1200g of 3M™ Thinsulate™ insulation, highly rated for extreme winter cold Boa®M4 Fit System for fast and effortless on/off and custom fit In-Shoe Comfort: Premium aerogel frost barrier footbed keeps the feet warm Durability & Traction: Customized traction on the fly; easily change soles as conditions or terrain demand Molded TPU toe cap for durability and protection with recessed stitching for added abrasion resistance Additional Details: Comfort rated down to -60 °F Height: 11 in. Weight: 4 lbs. 4 oz. per pair