The Knog Pop R rear light outputs 5 lumens of LED light with 180 deg visibility, to provide maximum rear illumination to fend of those pesky drivers. The rubber on/off button is cleverly located directly in the center of the lens for easy access. The button is sealed from the elements and features a 3/4 second delay to prevent accidental turn on. Short button presses switch modes continuously once the light is turned on. The grippy strap mounts to any bar with a hook and loop assembly, no tools necessary. The strap will fit any bars or frame tubes that range from 22-32mm in diameter. The Pop R runs on a single AA battery which is included with the light.