3 sizes available. Small: 18.9"-21.3" (48-54 cm), suitable for kids 2-8 years old. Medium: 21.3"-22.4" (54-57 cm), suitable for youth 8-14 years old. Large: 22.4"-24" (57-61 cm), suitable for people aged above 14.ABS shell resists impact and high quality EPS foam provides shock-absorbing. Complies with U.S. Consumer Product Safety Commission Safety Standard for Bicycle Helmets for Persons Age 5 and Older.11 top and side vents keep user cool and comfortable.Suitable for various outdoor sports such as cycling, skateboarding and so on.Fully adjustable, provided by the crank adjustment dial, 2 sets of pads with different thickness, and length-adjustable chin straps.
