Durable and Adjustable SizeMade of impact-resistant material. Imported high-density PC case with superior technology will surely improve the safety performance.Adjustable size: 54 - 57cm. Headlight Built-in Light and TaillightThe bicycle helmet has 3 white LED bulbs on the front, 10 red LED bulbs on the back.With the built-in light helmet, drivers, pedestrians and other cyclists will see you coming and warn cars or helping other cyclists behind you clearly recognized your direction. It is safer to cycle at night. USB Rechargeable Light with 3 Light Modes The light is super bright and has 3 light modes for option - Always on, slow flashing and fast flashing, which makes you shine in night cycling. High battery capacity: 750 mAh. The battery lasts about 6 hours constantly on mode. It is currently 3.78V, headlight power 150A, taillight power 314A. It is fully charged in 2 hours. Comfortable and safe The bicycle helmet uses aerodynamic design helmet and 14 ventilation holes to effectively reduce air resistance and sweat. This bicycle helmet is really light and fits comfortably while riding. Wearing this integrated lightweight helmet will protect your head in all directions and warn cars or help other riders behind you to recognize your direction clearly, more safe and brilliant in night cycling. The Package include: 1 x helmet, 1 x USB cable.Very convenient to carry the bicycle helmet outside or in the store.