Lupine Lighting Systems Rotlicht/REDLIGHT Tail-light: Bright, and BRIGHTER STILL with its genius functions - With incredible 160 Lumens of red light output, this is probably the most powerful tail light with an integrated battery - Brake Light - When you brake, the built in acceleration sensor turns the light brighter to gain more attention on the streets - Brightness Sensor - for example, as a car comes closer, the light turns brighter! You will not be overlooked on the streets anymore! The ROTLICHT is programmable to 4 different Light modes: Steady Light; Flashing Light; Wave Pulse Light; or Pulse Light All light modes can be adjusted in intensity from 0.1W (10 Lumens) to 2W (160 Lumens). Brake Light: When you brake, the built in acceleration sensor turns the light brighter to gain more attention on the streets. Brightness Sensor: Automatic ambient light adjustment. If, for example, a car comes closer, the light turns brighter. USB chargeable, replaceable Lithium Ion Battery