Keep the cold out and the warmth in with Heat Retainers by MUK LUKS Men's 1-Pair Heat Retainer Thermal Insulated Socks. Advanced thermal heat retaining technology will work to keep toes warm while stretchy knit fabric to allows for a flexible fit and easy pull-on style. Machine wash on gentle cycle, no bleach, tumble dry low heat. Imported. - 91% Acrylic, 8% Polyester, 1% Spandex Upper -One Pair Pack - Multiple color options available - OSFM (Men's Sizes 10-13)