FM Transmitter and Car Charger! We call this one "auto" because it gets its power from your vehicle's 12 Volt accessory outlet. And we call it "universal" because it works with any portable audio device that has a standard 1/8" headphone jack (including CDs, MP3s, cassettes, and yes, even iPod). Additionally, the "Plus" in this iTrip model is the ability to charge your player by means of a built-in USB port. Plug in your player's USB charge/sync cable, and you get to listen to your tunes while you're traveling, and arrive with a fully-charged player.