Easton's has pulled together Protechnology systems to deliver the helmet you have been waiting for! Drawing from the R&D and technology systems from engineers at Easton, Giro, and Bell, the S17 helmet offers the best in class fit, features and style. Lightweight, molded EPP liner Molded comfort pads with integrated wrapping on the front edges of the EPP liner In-Form Fit System: Microdial adjusts an internal fit band Patented system by Giro allows for customizable width adjustment for a true and comfortable fit and helps hold the helmet securely on the head Monolock tool-less length adjustment - Single Cam system located at the rear of the helmet is natural to use while wearing and allows the helmet to have a sleek profile Height adjustment earpieces can be easily adjusted higher or lower to your preferred height Superior ventilation - Easton has optimized the size and location of vents for an aggressive look and optimal airflow through silver mesh CSA, HECC, CE approved Fitting Information: helmet size - hat size / circumference Small - 6 5/8 - 7 / 20 7/8-22" Medium - 7- 7 3/8 / 22-23 1/8" Large - 7 1/4 - 7 5/8 / 22 3/4-23 7/8"