Features:  Automatic Light Sensation LED Lighting Bright but not Dazzling As equipped a 7-key high brightness LED lighting group, with automatic light sensation function, this bling helmet is capable of automatic starting up or standby according to the intensity of the ambient light. By adopting precise mirror polishing process, the lighting strip reaches a 180-meter visual distance, a sweet safe companion in the late night.  Waterproof Design All-weather Suitable The helmet employs an lPX4 waterproof design for allowing short exposure to the rain. For your safety, please do not expose to the rain for a long time while wearing it.  Size This cycle helmet allows adjust the head via the dial in the back and adjustable straps, they enable you to wear the helmet in the correct position for a feeling of reassuring comfort. Head Size: L: 22.44-24.02in (57-61cm).  No Mic and Speaker.   Integral Molding for Better Protection The exterior shell of the helmet employs PC (poly carbonate) material while the interior uses imported PSI-205T high density EPS (polystyrene foam). With an integral molding of external and internal layers, it dramatically strengthens the helmet impact resistance for safer daily journeys on the road.  Built-in 12 Vents for Excellent Ventilation The more vents of the helmet, the better ventilation and faster cooling while the protection body of the helmet, to the contrast, is lessened. On the premise of safety and good ventilation, we introduced the aerodynamics design concept and verified 12 vents as the optimal solution.    Specification:  Material: PC, EPS;  Color: Black;  Head size: 57-61cm / 22.44-24.02inch;  Battery: 3.7V 455mAh;  Working time: 36 hours;  Standard time: 180 days;  Charging time: 3 hours;    Package included:  1 x Bike Helmet