Material: Abs, Eps11 Air VentsSize: M(56-58)Dual Certified: Winmax kids helmets are certified by CPSC and Europes highest EN1078 Certification. Effectively reduce the risk of injury in multi-sports, such as BMX, cycling, bikes, roller skating, inline skating, skateboarding, and more. Protect Their Noggins: Crashes, falls, and tumbles are all inevitable. Protect their little noggins with the WIN.MAX helmets. Made of sturdy ABS outer shell and shock-absorbing EPS foam inner. Absorb external pressure and give maximum protection. Perfect Gift For Children: These fun patterns and styles are sure to get your little biking enthusiast excited to get out and ride! Painstakingly designed to look stylish and fun. Pure color helmets without patterns are also a good option when choosing presents. Light And Breezy: The lightweight, in-mold shell has 11 vents to keep your little rider cool all day long. The helmet's shape even encourages good bike posture. Suitable Size: Size S fits 18 7/8" - 21 1/4 ", while M fits 21 1/4 " - 22". The head circumference of the same age kids varies. So it would be better to choose the size according to the head circumference instead of the age recommendation. The soft straps and adjustment system are adjustable for a tighter and snugger fit and the quick-release clip keeps the helmet securely in place.