The softness of acrylic with wool's warmth. Wool and acrylic blend to keep feet warm and wick moisture away from feet. Fully thermalined leg and foot for shock absorption and insulation. Smooth linear looped toe seam for no irritation at toes. Heavy weight, mid-calf. 55% Duraspun® acrylic, 35% wool, 10% stretch nylon, except 2% Lycra ® spandex added to top.