Anatomical Interface System (AIS) is engineered to separate your toes with a CoolMax moisture wicking lining and a resistant nylon outer shell built with Lycra fibers, to create a thin, anti-friction membrane that is both lightweight and breathable. Seamless in construction, the tetratsok forms to every contour of your feet. This allows for true restriction free movement from your heel to five toes,encourages healthy circulation, and eliminates skin on skin contact between your toes to prevent blistering from occurring.