Bridgedale Stormsock Midweight Boot Length Waterproof Merino Wool Sock Black/Blue M100% Waterproof boot length sock with dense resilient terry cushioning throughout, ideal for outdoor activities where an increased amount of insulation is desired. Comprising 3 layers the Heavyweight boot length StormSock features dense resilient terry cushioning throughout the sock for warmth and padding The outer layer sock, made from nylon, protects the Hydrotech waterproof breathable membrane against abrasion from the boot.