Step up your game performance by donning a pair of the CEP Running O2 Progressive Compression socks. They offer the same benefits as the traditional Running O2 socks but with a stronger compression. These socks are worn worldwide by professional athletes and everyday sports enthusiasts who wish to elevate their game or shave down running time. The CEP Running O2 Progression Compression socks provide a firm 18-25 mmHg compression to improve blood circulation and oxygen supply to the legs for more energy and a quicker recovery time. The socks protect both feet and shins warding off shin splints and preventing blistering. Three sizes available (III, IV, and V) based on calf measurements. Black with gray trim and White with gray trim are the color options.