The Radio Flyer Helmet provides a cool way to be safe while riding. It has an interior adjuster that creates a safe, comfortable fit for heads sizes 48 - 54 centimeters. The helmet features a sleek, stylish look and an easy-to-use chin strap with safety buckle. For ages 2-5 years. For additional questions, support, or concerns, please contact our customer service team at https://www.radioflyer.com/customer-service/ or 1 (800) 621-7613.