Easy magnetic buckle Adjustable spin dial for individual fit Integrated LED light Scooter and bike approved Australian Standard Certified AS/NZS 2008:2063+A1:2009 The hand designed the water decal of the Doodle Spot and the 3D Dinosaur converge style and safety. The magnetic buckle makes safety even easier for kids - simply locking into place in one go before any scooting or cycling adventure. Kids love the fun yet lightweight designs! Available in S and M for pre-schoolers to kids protected with a firm safe fit. For sizing, measure the circumference of the head from the forehead where the helmet will sit, across the furthest point on the back of the head. Please do not guess. [XS] Extra Small: 46-50cm [S] Small: 48-53cm [M] Medium: 52-56cm How to fit your child's helmet Step 1 Turn dial at back of neck until helmet fits snugly. Step 2 Straps should form a 'V' just under the ears. Step 3 Front edge of helmet should be two finger widths above eyebrows. Step 4 When mouth is closed you should be able to fit one finger between chin and strap.