Powered by 2XU Compression technology, the Training VECTR Sock features 2XU's X:LOCK support system to optimize footstrike and push off, while also preventing abrasion. 2XU's X:BLEND fiber formula helps regulate body temperature and promote oxygenation of body tissues. Equipped with the Training VECTR Sock, athletes will enjoy enhanced foot performance and faster recovery. Features: - X:LOCK support system - X:BLEND fiber formula: celliant/nylon - Linked toe helps prevent blisters - Dry mesh panels - Cushioned heel + forefoot Sizing: - S: US Women's Sizes 4 - 6.5 - M: US Women's Sizes 7 - 9.5 - L: US Women's Sizes 10 - 13