ThinkGeek Personal Soundtrack T-Shirt Personal Soundtrack Shirt features a working speaker on the front and can play background music and sound effects at your command Pocket remote features 20 buttons and allows easy selection of 10 music themes and 10 different sound effects Easily load your own sound effects and music onto the Personal Soundtrack Shirt using standard MP3 files Play your iPod or other portable audio player through the speaker on the front of the shirt Black 100% cotton shirt, requires 4 AAA batteries (not included).