This cool helmet features: New matte finish for a modern, stylish look An ABS hard quality plastic outer shell with a lightweight inner shell featuring foam pads Clever magnetic snap-on buckle, pinch-free, with one-handed operation A spin dial in the back to ensure comfort and the perfect fit Air vents keep children cool Adjustable chin straps with quick-release buckle Tested and approved for Australian Standards S/M : Sized to fit head circumference 51-56 cm. Suitable for children from 4-10 years old.** **Age is only an indication. For the best fit, measure your child's head with a soft measuring tape horizontally around the widest point of the head, approximately 2 cm above the eyebrows.