The J.B. Field’s 40 Below Arctic Trail is one of the warmest thermal winter socks we make, containing 85% preshrunk wool! This style was designed for people who require a sock to keep their feet dry and warm in the most extreme conditionsas low as 40C!Pair these winter socks with a liner sock to help wick away moisture and keep your feet smelling fresher, feeling warmer, and blister-free.Pre-shrunk Wool: We use only the finest quality of easy-care wool in our socks because it is such a versatile fibre. It is breathable and moisture-wicking, and helps regulate body temperature by keeping feet dry, preventing blisters, and controlling odour.PLEASE NOTE: These socks run large. We recommend wearing a liner or sizing down, if possible.Sizes available:Medium (Men’s 48 Shoe / Women’s 59 Shoe)Large (Men’s 812 Shoe / Women’s 913 Shoe)X-Large (Men’s 1315 Shoe)Content: 85% Pre-Shrunk Wool, 15% NylonFull Cushion: Full Terry Cushion adds comfort, extra warmth, and protectionMade proudly in Toronto, Canada!