Seal Skins Chill Blocker Socks Mid-Calf Height, 11" Waterproof For Cold & Wet Conditions Outside Layer: Nylon & Lycra Spandex Middle Layer: Waterproof Mvt (Moisture Vaport Transpiration; Allows Perspiration To Escape While Not Allowing Water To Penetrate.) Inside Layer: Polar Fleeced-Lined With Polartec® Power Stretch™