ALIBRO Bluetooth Wireless Car MP3 FM Transmitter Modulator Radio Adapter Handsfree Car Kit with Music Control,Hands-Free Calling and USB Charging Port for iphones, ipods,other smartphones,MP3 Players and Other Devices Insert this FM transmitter into your vehicle's cigaretter or power port. Tune to your radio to a desired FM frequency,then match that same frequency on to the FM transmitter by using the buttons on the unit or on the remote control. Plug your compatible SD Card into the SD port or USB Flash Drive into the USB port of your FM Transmitter,or connect your other compatible Drive using the Audio Cable. If your machine has audio port,for other compatible music device or your MP3/MP4 player,connect to the Headset hole using the audio line,also to be able to launch car audio through the FM transmitter,let you enjoy the music! Line-in connector for audio players. There is a 3.5mm to 3.5mm adaptor for your mp3 mp4 player or other compatible audio device that have a 3.5mm audio jack.