Features of the Zamst HA-1 Run Sock Functional support and unique knitting Technology stabilizes the heel in a neutral position and lifts up the arch of the foot to prevent it from leaning inward a-Fit provides anatomically correct support for right or left body part Arch Support Knit construction ensures functional support for plantar fasciitis Flyweight Tech advanced material fabrication with lightweight construction Heel Lock Tech ensures proper Fit and enhanced heel stabilization V-Tech ventilated flow through design keeps you cool while in motion