Eco materials, extra padding, air vents to keep heads cool, adjustable side locking dividers, Fidlock magnetic buckle, rear sizing dial with integrated light. This helmet has been tested and approved according to European Norm (EN) 1078:2012+A1:2012. It conforms with regulation (EU) 2016/425. For safe, happy scooting, cycling and skating adventures Small: Fits head size 48-52cm. Medium: Fits head size 53-57cm. All child's heads vary and choosing the correctly sized helmet for your child has no correlation to their age. Please ensure to measure your child’s head before selecting your size helmet MICRO SCOOTERS Deluxe Premium Eco Sealife Helmet Small - Green