Step up your game performance by donning a pair of the CEP Running O2 compression socks. These socks are worn worldwide by professional athletes and everyday sports enthusiasts who wish to get an edge on their game or shave down running time. The CEP Running O2 compression socks provide a 12-18 mmHg compression to improve blood circulation and oxygen supply to the legs for more energy and a quicker recovery time. Three sizes available (III, IV, and V) based on calf measurements. Colors: Black, White, and Green.