KNOG Pop r Rear Light LEDS- 1x Super-bright SMT LED designed to provide maximum brightness for duration of run time. SIDE ILLUMINATION- Giving riders 180 visibility BIKE ATTACHMENT- Tool-less attachment for handlebars and frames of 22-32mm diameter. LOW BATTERY INDICATOR- A red LED will shine from the front of the light when the batteries are low. This LED will remain on for 5 seconds after the light is switched off to indicate that batteries need changing. BUTTON- Longer button push on (0.75sec) prevents accidental turn on. Short presses switch modes continuously.