Age range (description)Kid; toddler; teenSizec small: 19.5"-21.3" / 49.5cm-54cmOuter materialAcrylonitrile Butadiene StyreneAbout this productWhat You Will Receive- Made of ABS and EPS, light weight for kid's cozy wearing, and provides more safety. ABS shell resists impact and high density EPS inner shell and soft liner. Adjustable Multisport Kids Helmet- Before you use the helmet, please untie the buttons that connect the straps on both sides of the helmet. Depending on the size of your head, rotate the red adjustable knob on the back of the helmet and attach the button in the middle of the strap.Helmet with Protective Gear SetHelmet head circumference: 49.5-54 cm/19.5"-21.3", come with an adjustable helmet turning knob and adjustable straps which makes it flexible to fit perfectly for ages 4-8 boys and girls. Multiple adjustable elastic straps and velcro closures fit for various knee/Wrist/Elbow circumference.Use for:- This helmet could be used for many occasions to keep your kids safe, such as bicycling, roller skating, skateboard accessroies, scooter, hip-hop, rafting, head turning, mountaineering, river rafting, rafting, cave rescue, expansion, downhill, etc.Gift Ideas- Great holiday gifts for your boys and girls It is a good choice as Children's Day gift, Christmas gift, birthday gift and other festival gift.