This unit plays music from your iPhone using the external CD changer port to communicate with your factory radio. Next and previous song and charging are also done through the USB connection
Music from your iPhone through the USB port. No other connection is needed.
Next and previous song control from your Radio and/or steering wheel controls.
iPhone charging through the USB port.
3.5 mm aux port on the box. Will probably never be used but its there just in case.
This adapter connects behind the radio on all cars.