Sealskinz lightest, thinnest, waterproof sock. A mid-length, breathable sock, with Hydrostop. 100% waterproof, our lighter socks are perfect for running, hiking or any activity. The Aquasealz membrane releases body-generated heat and moisture, while denying the entry of water. Natural bamboo lining has strong moisture-wicking properties. Hydrostop prevents water entering the top of sock.