The Helix Sense 450 is quite possibly the brightest and most feature packed rear light ever made. The unique Sense mode includes a braking light which increases brightness when slowing down, brightness sensing which automatically switches between daytime flashing and night mode and parking mode which automatically turns the light to standby mode when no motion is detected. In addition, the Helix Sense 450 also has a group ride mode to allow you to be seen on group rides without dazzling your riding friends.SpecificationCOB red LEDMax. Lumens: 450LM (FL-1 tested)Max.Runtime:100 hrs (FL-1 tested)Battery Type : Li-PO built-inRecharge Time: 2:30 hrsSize ( W x D x H): 22 x 19.5 x 81 mmWeight: 40gKey Features5 modes: DAY FLASH / STEADY FLASH / FLASH 1 / MODE 1 / MODE 2CNC Aluminum heat sink casingSENSE ModeBrightness functionMotion sensing functionBraking functionParking functionLock ModeAuto safe modeDay flash modeMode memory functionVariable Lumen SystemLow battery, charging and fully cha