Heat Holders Thermal Socks. Thick, chunky socks made from a specially developed heavy bul yarn whcih has extreme thermal qualities. Brush inner traps warm air close to the skin keeping your feet warmer longer. Great for boots and spending time outdoors during the cold winter months. 91% acrylic, 5% nylon, 3% polyester, 1% elastine. Fits WOmen's size 5-9, solid assorted colors.