* The V stands for velocity and this tail light detects changes in riding speed and alerts surrounding traffic* High output surface mounted LED plus 2 5mm LEDs provide steady, Courtesyã¢, Superflash㢠& V modes* Velocity Variation Technology㢠accelerometer detects changing ride speed and alerts surrounding traffic with a four second burst of light* FL1 Tested - Run times: 8 hrs (steadyÛÒ4 lm), 10 hrs (Courtesy㢠-1-3 lm) and up to 36 hrs (Superflash㢠-4 lm) * Provide 180å¡ of visibility * Highly visible, even in daylight * Water resistance rated to IPX6 standard* 270 mAh lithium polymer battery charges in 2.5 hours with micro USB cable (included)* Smart Charging Technology㢠with built in low battery indicator* Includes seat post, seat stay and clip mount for multiple mounting options* Mount it to your rear rack with the Rack Bracket (#3108) which is sold separately* 54 grams