Helmet only
Lightest weight certified helmet available, More Breathable, Adjustable, Closable vents, Magnetic Quick Catch Chin Strap
Bluetooth Aviation radio Required For Talking to Airplanes
small / medium is 54 to 58 cm head size
large extra large is 58 to 62 cm

How to Measure Your Head
Place the string or tape around your head about 1/8″ above your ear, across the mid-forehead, completely circling your head. Hold the tape firmly, but not too tightly. If your measurement falls between sizes, choose the next largest size.