JaJaBor Car FM Transmitter Dual USB Car Charger Voltage Detection Car Mp3 Player Bluetooth 5.0 Handsfree Car Kit FM Modulator Please note : there is no blue light with the two 12V cigarette lighter sokets, the pictures are renderings for your reference. 1. Input DC 12--24V, output DC5V 3.1A charging port 2.U disk Mp3 TF Card Mp3 Bluetooth mobile phone to play music,the song/next song key conversion 3. Car battery voltage display 4. Mobie phone Bluetooth hands-free phone/access keys/ with optional 5.FM emission frequency adjustable(press and hold the middle key until the screen flashes, and press the up/down key to adjust the frequency) 6. Adjustable volume(long press the up / down key to adjust the volume) Package Includes: 1x Car handfree FM transmitter Question and Answer Question 1: What is the FM transmitter? Answer: FM transmitter is a very small FM Radio Transmit Station with a broadcast range of <5 meters. Main function: Transmit the audio to your car FM radio via the same FM bands, Then you can hear this audio in the car speaker. Question 2: Why my car FM Transmitter function is so noisy? Answer: FM Transmitter transmits the FM band in 5 meters. We know the FM radio station is a very wide range, if we set the same band with radio, our signal will affect a lot. So we can follow the steps as below, 1. We adjust our car FM to the band without the radio station, like 108.0MHz. 2. We change our device FM band to the same band with car FM -108.0MHz. 3. We can play music via TF card or Bluetooth, check the quality of sound. Question 3: When playing music, get an incoming call, why the sound volume becomes louder or lower after answering it? Answer: Because the calling volume is controlled by the "Calls "and music volume is controlled by "Media "in your phone volume settings. So you can modify the settings on your phone to let the sound more comfortable.