HDE Rock DJ Equalizer Sound Activated LED T-Shirt T-Shirt lights up and reacts to various sound levels with adjustable sensitivity; T-Shirt made from 65% Cotton, 35% Polyester Battery pack with belt clip is built into the t-shirt, interchangeable with other LED panels with the same adapter type LED panel and battery pack can be removed from the shirt and be integrated with other apparel or used for interior decoration Size: M, L, XL; Color: Black (shirt); Batteries: 2 x AAA (not included); Package Contents: 1 x T-shirt w/ battery pack, 1 x Equalizer LED panel HDE is a registered trademark and is the only authorized seller of HDE branded products