LED Sound Activated E-Q Raver T-Shirt (Double Extra Large) [Electronics] Black cotton t-shirt with a sound activated illuminating panel. Adjustable volume sensor for the flashing speed. The lights flash in green, yellow and red in time to music and sound. The battery pack has an on/off switch so you can choose when you do and don't want to flash (as it were). The battery pack can be unplugged for washing the t-shirt.