Hornit Children's Bike Helmet in Small: 48-53cm and Medium: 54-58cm. A helmet is only as good as its fit. Maximum protection demands a snug, well-aligned fit that is comfortable, yet secure. This is why Hornit helmets feature a fully adjustable ring adjuster - rotate right to tighten and left to loosen. Our three-way adjustable chin strap and the strong and secure buckle ensures the helmet always stays in place. Removable soft foam allows further flexibility for size and fit during growing years. Made from durable, weather-proof plastic, Hornit helmets protect your kids as they brave the rain, snow, and wind. Eleven air vents on each helmet ensure even air flow to keep them cool and comfortable. The rear safety light alerts distracted drivers or pedestrians to your child's presence. Combining style and safety, Hornit helmets come in a range of fun designs.