Certified conformance to medical standard - BS6612. Designed to improve blood flow, which in turn helps to flush lactic acid during, and post, training and racing. Provides circulation improvement and an improved recovery rate. This compression sock also reduces calf muscle oscillation. Made from Tencel® for a super soft hand feel and from LYCRA® SPORT to ensure a close, comfortable fit.Socks designed and manufactured by HILLY, the UK's premier technical performance sock company for runners - founded by Ron Hill.