The High Calf Boot Sock is a terry loop lined, mid-weight sock that extends to the high calf. This provides for added warmth when outdoors in the cold for a long period of time. People wearing boots or higher topped shoes may like this sock over the crew length. It has two calf bands that are made of acrylic and dyed black; to ensure this sock stays up all day long regardless of the activity! It has a reinforced heel, toe, and arch-band for a proper fit. Like all alpaca products it is hypo-allergenic, not prickly, and very comfortable and warm. Alpaca is a hollow fiber that wicks away moisture. This is important for people who have feet that perspire.