Car x-8 bluetooth fm transmitter car radio adapter dual usb rapid fast charger compatible with all smartphones supports calling and usb mp3 player tf card and u disk, fm transmitter when you are calling or-appreciating music. fast dual usb charging - bluetooth fm transmitter is equipped with 2 usb ports, the qc3.0 port supports 3a/2a/1.5a charging, the other is normal 1.0a charging and supports usb music play.