High-density, impact resistant ABS outer shell - Shock absorbing , thick EPS liner - Adjustable chin strap - Strategically positioned air vents - 2 sized liners for optimum fit - CPSC certified - MBS logos graphics. Artwork by Dan Wilson. SIZING: Run a tape measure around your head just above your eyebrows to get an accurate measurement. 19" - 21" = S/M 21" - 24" = L/XL