The reflex auto will automatically turn on whenever both darkness and motion are detected by the motion and light optic sensors providing the rider safety both while the light is turned on and while functioning solely as a reflector. 5 leds greater than 180 degree visibility automatically turns on off by light and motion sensors emits light for 50 seconds after the bike stops built in reflectors that meets highest government standards usa great britain europe and japan opticubetrade lens technology aaa alkaline battery x 2 5 modes mode memory function sp 5 bracket oslash21.5 31.8mm and rear rack bracket weight 82g designed in japan runtime constant mode6530630hrs flashing mode65306100hrs rapid mode6530660hrs long life mode65306120hrs pulse mode6530630hrs technologies auto lightauto on off controlled by motion and optical light sensors to automatically turn the light on when darkness of motion is detected. Reflectorour reflector technology exceed the highest government standards around the world. Opticubetradeour proprietary opticubetrade lens technology maximizes brightness for greater visibility. Side visibilityprovides visibility from the side to increase safety. All weathercan be used in rainy weather.