Designed for maximum safety with an adjustable spin dial, an integrated LED light and extra padding the Micro helmets are engineered for an ergonomic fit for pre-schoolers to kids. The magnetic buckle makes safety even easier – simply locking into place in one go. Adjustable safety straps and air vents keep heads cool ensuring comfort comes with safety. Please note that only Doodle Dot, Unicorn and Rocket pattern are available in the XS. 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.