The Electro Luminescent T-Shirt has a built in graphic equalizer panel that is sound sensitive. As the music beats, this special T Shirts equalizer lights up to the beat of the music.It has a fully functional EL (Electro Luminescence) panel with a battery pack that snuggles discretely into a pocket inside the shirt.Each frequency of music will activate a different equalizer bar. To activate your Jack-O-Lantern Pumpkin EL Shirt, find the battery house stored in a little pocket at the bottom hem of shirt. Next insert in the batteries we provide for you. Flip the switch & turn the wheel that controls just how sound sensitive you want your shirt to be. You can also dim it to save battery power. NOTE: DO NOT wash the shirt with the battery pack still connected. It all detatches easliy and it's simple to reconnect after shirt is dry. LINE DRY your shirt to ensure no shrinking. Size: Adult Small Batteries: Includes 2 replaceable AAA batteries. - Weight: 0.56 LB