Typhoon 3/4 Helmet With Face Shield & Tinted Sunshield DOT Motorcycle Scooter Moped Cruiser Helmet - Gray White - Medium Certified to meet the DOT standard (FMVSS 218), Polycarbonate composite shell is lightweight offering superior fit and comfort One-touch integrated smoke tinted sunshield, Air intake and exhaust events Moisture-wicking and comfortable interior with removable/ washable liner and cheek pads High range optical view shield with anti-scratch coating SIZE CHART (Circumference of the largest part of your head, usually just above the eyebrows) in inches SMALL: 21 to 21  - MEDIUM: 21  to 22 - LARGE: 22 to 22  - XL: 22  to 23 - XXL: 23 to 23 . Head shapes can affect how a helmet fits. The size chart is meant to be a starting point; Shipping for exchanges will be at an additional cost. Retractable tinted sun visor for added convenience Removable &amp; washable liner cheekpads High range optical view shield with anti-scratch coating Sculpted aerodynamic ABS shell offering a sleek and lightweight design Advanced front flow ventilation system with channels for maximum venting and comfort Standard D-Ring closure chin strap Take a head measurement with a cloth tape measure. Wrap the tape measure around your head one inch above your eyebrows, directly above your ears and to the widest area at the back of your head. This will give you the circumference, which is the measurement displayed below.