VICTGOAL Kids Full Face Helmet with Button Cell Taillight Suitable for children with a head circumference of 52-56cm/20.47-22.05inch. *Attention: 5-14 years old is only our recommended age, please purchase based on the actual head circumference measured by children! Please measure the child's head circumference before purchasing to avoid the child being unable to wear it. The tail lights are button cell tail lights, battery by CR1632.