SealSkinz Thetford Waterproof Oversocks - Black X-Large. The original waterproof ankle length cycle oversock is lightweight and streamlined. Designed for use with cleated cycling footwear making them suitable for both road cyclists and commuters in a wide variety of weather conditions.A unique three layer construction with a 100% waterproof hydrophilic membrane ensures that no water penetrates your oversock keeping your shoes dry as well as your feet.