To activate your UV Reactive LED Noodle Headband Flashing Dreads, press the button located in at the center of the headband for 3 light modes: Fast flash, slow flash, steady light. For an extra good time, wear these noodles to a UV party and watch the noodles and lights glow even brighter! LED colors: Purple Dimensions (W x H): 5.25″ x 7.5″ Noodle Headbands include 3 replaceable AG13 Batteries.