The smart lunar r2 usb rear light is a small rear bike light which uses a usb rechargeable batteries the light has a great construction and produces a light which is powerful enough to be visible up to 1 mile this smart rear light has 4 light functions and a run time of upto 25 hours depending on what mode you choose smart lunar r2 usb rear light features one 2 x 12 watt rear red light aaa batteries included visible from up to 1 mile light functions 4 steady flashing 12 watt onl