The Heat Machine Men's Lightweight Thermal Insulated Socks are a high quality, acrylic thermal insulated pair of socks. They are engineered for your feet using the finest triple brushed acrylic yarns with extra long terry to create a thermal barrier to keep warm air close to your skin, ensuring your hands stay warmer for longer. This material and construction is what makes them a thermal insulated sock. They are constructed with easy grip tops to help ensure all day comfort.