AIRfeet SPORTS O2 Dynamic Active Arch Support Technology, have been upgraded with additional advanced energy absorbing upper layer for Impacting Sports and lifestyles. Truly revolutionary and a game changer! 4 Unisex SKUs. - S (M 3.5-6.5; W 5-8) - M (M 7-9; W 8.5-10.5) - L (M 9.5-12.5; W 11-14) - XL (M 12.5W-15.5; W 14W-17.5) SNIP & UNZIP trimming provides the customer with the most intelligent yet simple method of trimming to their size if needed. Targeting: - Tibial Shock, Plantar Fasciitis, Flat Feet, Joint Pain, Foot & Knee Pain, Back & Hip Pain. Designed For: - Playing, Running, Jumping, Competing Benefits: - Advanced Energy Absorbing Upper Layer - 80% Dynamic Arch Support, - Feather Light, - Reversible, - Machine Washable, - Compliments Orthotics - 12 Month Warranty Foam Upper Layer Polyester Lower wicking fabric Patented TPU Air Chamber Design