In mold polycarbonate outer shell 46-51cm Dial Lock for simple size adjustments 3 Mode LED Flashing light on rear for added safety and extra visibility Sealed Foam pads for maximum comfort and Safety Australian Standards Approved bicycle helmet Light Weight Approx 235grams NOTE: The age guide above is approximate. Getting the right fit is very important. To measure your child’s head, use a measuring tape and measure around the widest point of the head which is about an inch above the eyebrows.