Carhartt A66 Extremes Cold Weather Boot Sock. 63% acrylic, 16% wool, 6% polyester, 14% nylon, 1% lycra-spandex. Boot length, heavyweight sock. Fully cushioned foot and lower leg for comfort and warmth. Non-terry vamp with breathing vents reduce bulk at ankle for comfort and breathability. "No feel" toe seam. Reinforced heel and toe areas. Anti-odor fabric treatment.