Size: 48-54cm (2-9 years old children a head worn)
Adult head circumference 55-60cm (10 years wear)
Tip: the slow development of 10-12 years old children may still wear children's section, the actual size of their amount!
Limited by natural light, incandescent light, ultraviolet light exposure at night, the light energy is stored. After the cessation of light exposure, slowly released by fluorescence, so at night or dark place can see the light for a period of time.