Dual USB Port & Safe Charging- It has two USB charging ports, one supports 1A charging and one supports 2.4A charging. It can charge two devices at the same time and has overcharge protection. The device is safer when charging Hands-free Calling- Bluetooth 5.0 transmission technology allows fast connection and stable signal. Automatically connect memorized paired when power on. Rotate function button allows you to easily select FM channels and Play/Pause/Answer/Hang up phone calls Unique LED Design- This FM transmitter designed with blue LED lights, you can see the button clear in the darkness. It will automatically switch on and show the battery level of your car. Make it easier to operate and drive safely when driving at night Excellent HI-FI Crystal Clear Stereo Sound- Built-in microphone with CVC noise reduction technology to create full duplex sound quality offer you hands-free talking and navigation voice broadcast. Full FM radio frequency range from 87.5 to 108.0MHz is wider than what ordinary transmitters Widely Compatibility- This upgraded FM transmitter supports play music via Bluetooth, TF card and USB disk and it will automatically detect and play the MP3/WMA/FLAC/WAV/APE format music . Compatible with most devices on the market. The packaging includes: 1pcs * in car MP3 Q1: What kind of car model is the device suitable for? A: This device fits all vehicles that have a cigarette lighter and a radio. Even very very old vehicles Q2: How to use the FM transmitter? A: 1. Plug it into the car cigarette lighter socket, and it will turn on automatically. 2. Connect your mobile devices with this car Bluetooth transmitter, or insert a USB flash drive or TF card into the transmitter. 3. Tune your car stereo to a blank, unused FM frequency. The standard is a slight rustling sound. 4. Adjust the Mohard FM transmitter to the same frequency: Rotate the MFB or press the "Next/Previous" button to increase/decrease the frequency. At this time, the car radio will be very quiet, with no static interference. (If it's still not quiet, try to find a new blank channel again) 5. Then you can listen to songs from your phone and make hands-free calls on your phone. Q3: How to solve the noise problem? A: 1. Try a few more clean empty channels to match, only rustling sound, no human voice and radio interference are clean empty channels; 2. Adjust the transmitter FM channel to be exactly the same as the car FM channel; 3. Turn down the volume of the car speaker, and increase the volume of the mobile phone and car Bluetooth to reduce noise appropriately.