To ensure a perfect wrist guard fit, measure hand circumference at the knuckles and match to the sizes listed below: * Jr 7.0 - 7.5 inches - S 7.5 - 8.0 inches - M 8.0 - 9.0 inches - L 9.0 - 10.0 inches * Tough, 4-way stretch nylon mesh provides a snug fit - High-density, impact-resistant molded ABS splints on front and back for support * Shock absorbing EVA foam secured between support splints and wrist for cushioning - Ideal for inline skating (roller blading), roller derby and all roller sports