The alpaca terry loops are formed so the nylon skeleton of the sock is covered with alpaca yarn on the outside, increasing the hand of the sock greatly. You will know instantly how warm and cozy these socks are once you pick them up. USA Alpaca has been knit into the sole and toe of the sock. Our High Calf Boot Sock is an alpaca terry loop lined mid-weight sock that extends up over the calf for added warmth in the great outdoors. Two calf bands on the leg and a snug arch band ensure the sock will stay in place and fit comfortably throughout the day. The heels and toes are reinforced with high performance nylon for increased durability. USA Alpaca is knit along the sole and toe. Hypo-allergenic and odor resistant. Contents: 75% U.S. Alpaca, 23% Nylon, 2% Lycra.