The original, 100% waterproof, windproof & breathable mid length sock. The inner lining is crafted from fine Merino Wool to insulate and regulate temperature making this perfect for use in very cold conditions. Technology: We pioneered the use of a unique hydrophilic membrane that&';s 100% waterproof yet pulls moisture away from your skin at the molecular level -- keeping you dry and cool all at the same time. And with a Hydrostatic Head of >20,000mm, our socks stay waterproof under the toughest of conditions. Materials: Our 100% waterproof socks are constructed using premium materials and by bonding three layers together to make one highly waterproof and breathable sock:a Outer Layer - 90% Nylon, 10% Elastanea Middle Layer - 100% Hydrophilic Membranea Inner Layer - 41% Merino Wool, 41% Acrylic, 14% Polyester, 2% Nylon, 2% Elastane Waterproof Sock Care: We don&';t like complicated things. And when it comes to the care of your socks, we want to make it as simple as possible. This is the type of sock you can throw in the wash along with the rest of your gear. No need to line dry or wash with special detergents. Since the membrane is a solid barrier, you&';ll never need to re-waterproof.a Wash at 40degC/105degFa Low Tumble Dry or Drip Drya Do Not Dry Clean, Iron, or Bleach Size Guide: Socks S M L XL UK shoe size 3 - 5 6 - 8 9 - 11 12 - 14 Euro shoe size 36 - 38 39 - 42 43 - 46 47 - 49 US shoe size (Men) 3.5 - 6 7 - 9 10 - 12 13 - 15 US shoe size (Women) 5 - 7 8 - 10 11 - 12