Working : (USB can't be used separately);(1). With 3.5MM Audio Cable:Plug the device into the USB interface, the blue light flashes quickly, and connect the device to the car AUX interface with a 3.5MM audio cable (or plug the audio cable of the speaker into the device). Turn on the phone Bluetooth, and search for the Bluetooth device -128, The blue light flashes slowly after successful connection. (2) FM Transmitter:1.Connect the device to the USB port of the car lighter or the USB port. USB port of some cars can't be used or the noise is large. It is recommended to use the lighter to supply power. 2.Three Frequency: 87.5MHZ (green light on), 88.0MHZ (red light on), 88.8MHZ (green and red light on), click the button to change the frequency and set you want;3. Adjust the car radio frequency the same as the device. When the device has interference or the noise is large, you can fine tune the radio frequency by 0.1 MHZ or minus 0.1 MHZ, or change to another frequency. 4. The device has frequency memory function. When the you turn off the device under 88.8MHZ frequency, it will be 88.8MHZ when you turn on the device;5. Turn on the phone Bluetooth, and search for the Bluetooth device -128, the blue light flashes quickly, and the blue light flashes slowly after successful connection. 6. Turn on the mobile phone music player, you can send the phone music to the car radio. It is recommended that setting the car volume to moderate volume, only setting the phone to get the volume you want. Because the car volume is louder, the noise and distortion will be more serious. Bluetooth Handsfree Calling: When you have a phone call, short press the button to answer, long press to reject. Specifications: Product Model: -128 Bluetooth Version: V5.0+2.1EDR Bluetooth Distance: 10M Launch Distance: less than 8M Working voltage: DC5V/2.1A(MAX) Power supply mode: USB power supply Applicable Equipment: Speakers/ Car/Radio/Amplifier colour: black Material: PC + metal size: 6 * 2.3cm Package Contents: 1 * Bluetooth 5.0 FM Transmitter Receiver 1 * 3.5mm audio cable 1 * User Manual Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.