Shock Doctor SVR Recovery Compression Socks Active muscle support: supportive compression to reduce muscle inflammation, soreness and fatigue Ventilation: targeted AirFlow mesh and moisture wicking fabric increases cooling to help regulate muscle and body temperature Real-Time Recovery: gradient compression to enhance circulation and increase oxygen flow to accelerate lactic acid removal so muscles can recover quicker. Sizing Chart: SMALL = Men 4-6 / Women 5-7; MEDIUM = Men 6-9 / Women 7-10; LARGE = Men 9-11 / Women 10-12; X-LARGE = Men 11-14 / Women 12-15