About this item CONSTRUCTION AND SAFETY;Complies with U.S. Consumer Product Safety Commission Safety Standard for Bicycle Helmets;In-mold outer shell construction, shock absorbing polystyrene inner,3D bold graphics that kids love SIZE ADJUSTER;There is a dial at the back of the helmet for easy one-hand size adjustment,It fits for head size 48-52CM COMFORT;Vents keep the helmet light(0.5lb) and ample air intakes，Perfect for many kind sports such as bicycle,Roller-Skating,scooter,Ties and adjusts easily INTERIOR;Anti-allergenic interior padding is hand washable and an insect net is built in COLORFULL TAILLIGHT；With Colorful Taillights Make your child stand out