The Bridgedale StormSock Midweight Knee consists of three layers and features a firm, elastic terry footbed, heel, and ankle for warmth and cushioning. The socks are primarily made from merino wool, known for its antibacterial, odor-resistant, and moisture-wicking properties. They keep your feet warm and dry. The outer layer made of nylon protects the waterproof, breathable Hydrotech membrane from abrasion caused by the boot. The stretch PU membrane and the clever matrix lamination process that connects the three layers of the Bridgedale StormSock ensure top-notch stretch and wear characteristics. Details: 100% waterproof and breathable. Wrinkle-free. Elastic fit. Weight: 164 g/pair (size M). Available in sizes: M/40-43, L/44-47.