Z1R Jimmy HelmetAdvanced abs polycarbonate alloy shell passes DOT standardsDual forehead vents are closable and direct air into the helmetComfortable brushed nylon interior with padded chinstrap3 snap removable bubble visor5 snap shell design will accept most face shields (not included)Spacious ear pockets for accepting speakers Z1R HELMET SIZING CHART SIZE HAT HEAD(CM) HEAD(IN) Medium 7 1 8 7 1 4 57 58 22 3 8 22 3 4 Large 7 3 8 7 1 2 59 60 23 1 8 23 1 2 X Large 7 5