Package Included: Helmet * 1 USB cable * 1 Feature: Material: Integrated PC shell, effective impact resistance, wear resistance and drop resistance. Thickened EPS liner with cushioning effect. Lighting highlights: Equipped with illuminated headlights + warning taillights, the headlights are in constant mode, the taillights are adjusted in three gear modes, constantly on-fast flashing-explosive flashing, safer riding at night. Battery: 750mah rechargeable lithium battery, USB charging mode, can be fully charged in 2.5h, the most power-consuming mode can last more than 10h. Size optional: There are adjustable knobs on the back of the head, M: head circumference: 54-57cm, L: head circumference: 58-61cm. Applicable scene: cycling, balance bike, skateboard, etc. Description: Product name: Protective helmet Material: PC shell, EPS liner Product highlights: lighting headlight + warning taillight + USB charging Headlight mode: white light is always on Tail light mode: constant light-fast flash-burst flash Size S,Head circumference:48cm-53cm Size M,Head circumference:54-57cm Size L,Head circumference:58-61cm Battery: 750mah, 2.5h full charge, the most power consumption mode can last more than 10h Applicable scene: cycling, balance bike, skateboard, etc. Notes: 1.Due to the difference between different monitors, the picture may not reflect the actual color of the item. We guarantee the style is the same as shown in the pictures. 2.Due to the manual measurement and different measurement methods, please allow 1-3cm deviation. Thanks!