It's a mini disk of plasma light! With a built-in battery compartment, this Rainbow Pocket Plasma Clip-On Mini Disk is completely wireless. So, you can take it anywhere and clip it anywhere... even in your car! It features 2 modes to choose from (sound responsive or straight plasma flow), a built-in clip for easy attachment, and super-bright technology… all combined with miniature electronics to create a flat-panel disk with a fantastic display of plasma light that will respond to your touch or voice, or dance to your music! Requires 2x "AAA" batteries (not included). Item measures 2 3/4-inches in diameter x 1 1/2-inches wide. Take it anywhere, and impress!