Limited Edition Designs No-pinch Magnetic Buckle Adjustable Spin Dial for Individual Fit Integrated LED light Scooter and Bike Approved Helmets Australian Standard Certified AS/NZS 2008:2063+A12009 With an adjustable spin dial, an integrated LED back light and extra padding. Micro kids helmets are engineered for an ergonomic fit. The magnetic buckle makes safety even easier – simply locking into place in one go, pinch free. Adjustable straps and air vents keep heads cool ensuring comfort comes with safety. 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.