These adapter cables provides a direct audio input from any RCA audio source such as an iPod, MP3 player, DVD player, video game, etc. to your car's factory radio, using the factory radio's external CD changer input, rear seat entertainment input, or optional satellite radio input on some models. By using the auxiliary input a line-level full bandwidth audio signal is passed into the radio, providing the highest musical sound quality- much better than any FM transmitter or headphone adapter can provide. These direct audio inputs are only compatible with radios that are CD changer ready, came factory equipped with an external CD changer or rear seat entertainment, or in some cases are satellite radio ready. Note: if the vehicle is equiped with a CD changer it may have to be disconnected so the auxiliary input can be connected.