Monoprice FM Transmitter Optional Charging USB Port (110403) So you love listening to your own music, but don't have an auxiliary port or tape deck in your car? What you need is this Mini FM Transmitter from Monoprice Simply select an open radio frequency on the FM transmitter, and tune your radio to the same frequency This FM transmitter can transmit the selected FM frequency to your cars radio in order to play music from your smartphone or MP3 player