EXO-C110 Half Helmet AzaleaFeatures: Advanced LG Polycarbonate Shell SpeedView Drop down Sunvisor KwikWick II Anti Microbial COMFORT Liner Removable ear flaps have Pockets for Speakers Communication Device Aero Tuned Ventilation System Low Profile Peak Visor Dual Density EPS Liner DOT APPROVED HELMET SIZING CHART SIZE INCHES CM HAT SIZE X Small 20 7 8 21 1 4 53 54 6 5 8 6 3 4 Small 21 5 8 22 55 56 6 7 8 7 Medium 22 7 16 22 3 4 57 58 7 1 8 7 1 4 Large 23 1 8 23 5 8 59 60 7 3 8 7