Denew FM transmitter, Bluetooth car radio audio adapter, FM modulator car MP3 player hands-free car kit supports 5V 3.1A dual USB ports/voltage detection, play USB disk/SD card Easy to use: Plug the Bluetooth FM transmitter into your car cigarette lighter; tune your car radio to an unused FM frequency (ranging from 87.5 to 108 MHz) and then match the Bluetooth FM transmitter to the same frequency; pair this car kit device with your mobile phone/tablet via Bluetooth. You can then listen to your favourite songs or make phone calls. If there is an incoming call, the unit will automatically switch to phone when you are in music playback mode. Hands-free calling: The in-car FM transmitter adapter with built-in microphone and noise suppression (CVC) technology provides crystal clear calls while allowing you to drive more safely; answer/redial/hang up calls/reject with the push of a button. Dual USB ports: The Wireless Audio Phone Car Kit accessory supports charging of two devices at the same time, together outputting 3.1A. The built-in smart chip (charging IC) will automatically divide the voltage according to the needs of the device. Play music: The smart MP3 audio music player allows you to listen to your favourite songs by inserting a USB flash drive/TF card reader which contains MP3 files into the correct USB port. This portable electronic FM transmitter can also transfer music from your mobile phone via a Bluetooth connection. Extensive compatibility: this Bluetooth in-car FM transmitter is compatible with most Bluetooth-enabled devices such as smartphones, tablets and other Android smartphones; stream music and calls directly from your mobile phone mobile device to your car audio system speakers via the FM radio signal.