SEEMEE 100 V2.0 Smart Bike Tail LightTransparent optical fiber provides maximum 100 lumen output. 260 lighting visibility gives you all around protection. 5 modes: low, high, flash, eco, smart. Built in motion sensor automatically turns brighter when braking (can be turned on off manually). Ambient light sensor automatically adjusts modes according to the environment. Low power mode (automatic) to extend the runtime efficiently. Multiple mounting methods that fit in saddle and different