The Scosche FMTD7 freqOUT allows you to play music through your car stereo from your iPod or iPhone. The innovative design of the freqOUT lets you charge your iPod or iPhone while you play your music. The digital FM transmitter plugs directly into the bottom dock of your iPod or iPhone to provide a clear and crisp audio signal. For other phones and MP3 players without a 30-pin dock, use the included auxiliary cable to plug directly into any headphone jack. The freqOUT mounts into and is powered through any 12v power socket in your vehicle.