Zamst All Sport HA-1 Compression Support Run Sock G-Fit, Color Choices 775300. The HA-1 Compression with G-Fit technology delivers vertical gradual compression from the ankle through the calf muscle. This improves circulation to encourage blood and oxygen flow to the muscles. The G-Fit Tech also aids with flushing out bi-products (lactic acid), reducing muscle vibration and fatigue, which improves muscle endurance and recovery. The HA-1 Compression sock has built in a-Fit technology provides anatomically correct support and fit for the left and right foot. The HA-1 Compression?s 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. This will minimize the stress from repetitive impact on the foot to reduce plantar fasciitis. Color: Multiple color choices. 775300