This lamp features in auto-control of light and provides five light modes. Under any of the five modes, the lamp turns off by itself when it stays still in about 3 minutes, and can be activated by movement. Only in Automatic Mode, the light sensor works. The lamp becomes bright when ambient lux level is low, and turns dim or off when the ambient light is bright. Important: Please be noted this function may not be fully up to your expectation as personal preference to the ambient lux level might be different. Specifications: Item: Bicycle Front Light Light source: Cree XPG Cool Day White, and Two Yellow side LEDs Output: 400LM Max Reflector: Mirror-surfaced Light Mode: 5 modes (detailed in the graphics below Switch: Press button to turn on/off, or change modes Battery: Li-Polymer batter built-in, 800mAH, Rechargeable Charging: USB 5V 1A Max ( Android type port ) Run time: Approx. 2-24 hours, subject to mode in use Ingress protection: Rain water resistance, do not use in water Net weight: Approx. 76grams (Incl. bracket) Features: Smart bicycle head light, may be activated by movement; With light sensor. Self-tuning of brightness to ambient lux level changes; Comes with 5 light modes to meet various options; LED chip mounted at inner top side, avoiding direct glare to the strong light; Well-formed reflector & diffuser, ensuring even light distribution; side visible; Genuine Cree chip offers daylight white lighting & stable performance; Featuring in yellow warning light for use at daytime or low lux places; Built-in lithium battery, USB rechargeable;