Sizing Youth Helmets for MX Measure the circumference of the head just above the ears and across the forehead. Refer to the chart for proper helmet size. Size Head Youth SM 18-1/2” - 19-1/8” 47 / 49cm Youth MD 19-1/4” - 19-7/8” 49 / 50cm Youth LG 20” - 20-1/2” 51 / 52cm Specs & Features AR1 Series: Shell made of injection molded Acrylonitrile Butadiene Styrene (ABS) Sculptured, dual-density, EPS impact absorbing liner Removable/washable liner is made with moisture wicking fabrics Flexible rubber nose piece helps deflect roost Two large front air intakes and four rear exhaust vents help keep you cool Meets or exceeds ECE 22-05/06 and D.O.T. FMVSS 218 safety standards AR1 Sweep Series: Shell made of injection molded Acrylonitrile Butadiene Styrene (ABS) Sculptured, dual-density, EPS impact absorbing liner Removable/washable liner is made with moisture wicking fabrics Flexible rubber nose piece helps deflect roost Two large front air intakes and four rear exhaust vents help keep you cool Meets or exceeds ECE 22-05/06 and D.O.T. FMVSS 218 safety standards Product Description The AR1 helmet is Answer Racing's best value helmet, all while meeting or exceeding D.O.T. and E.C.E. safety standards. A dual-density EPS liner helps to absorb both large and small impacts while a highly developed ventilation system consisting of multiple intake ports and exhaust ports help keep you cool in warmer weather.