Be visible day or night with this unique and super powerful rear light flashing mode automatically boosts output to 100 lumens during the day to make you visible up to a third of a mile or half a kilometre in full daylight for up to 14hrsup firing red leds w patent pending reflector design for light that projects back long distanceflashing mode auto boosts output to 100 lumens in daylight for increased visibility3 nighttime modes w outputs between 50lms 25lms and runtimes between 6hrs 17