US Sizing Guide - Unisex S/M Shoe 5 to 9 Calf 9in to 15in L/XL Shoe 8 to 15.5 Calf 14in to 19in Unlike normal athletic socks, OXYVEN Socks are designed with gradient compression, The perfect performance designed for any activity where your legs are pushed to the limit. OXYVEN Socks are engineered with the latest arch to calf compression technology, offering a targeted foot to calf muscle support unseen on lesser quality socks.The results are a boost in circulation, delivering an enhanced blood flow keeping you going harder, for longer, and recovering faster. As a small family business, our customers are at the heartbeat of everything we do. We have designed our products from the ground up, with the premium quality customers deserve. Fits for : Suffering from varicose veins, foot pain, leg pain Pregnant woman, Nurses and doctors Athletics, fitness lover, runner, cross-fit Masseurs, cosmetologists, and stylists Frequent travelers or anyone taking a long plane flight Teachers, Warehouse, packing, or delivery occupations Business people with desk positions that require prolonged sitting Construction workers, chefs, line workers, and restaurant serving staff Jobs that require you to be on your feet a lot and MORE!