What is the difference between the iTrip Auto Universal and the iTrip Auto Universal Plus?

The iTrip Auto Universal plugs into the headphone jack of your mp3 player. The other end plugs into the power outlet of your car. The car's outlet powers the iTrip Auto's FM transmitter, but it does not charge your mp3 player.

The iTrip Auto Universal Plus has an additional female USB jack so you can make use of all the features described above AND charge your mp3 player at the same time. If your mp3 player uses a USB cable, you can use this cable with the iTrip Auto Universal Plus to charge your mp3 player while transmitting the audio to your FM radio.