Features1. Start up and check the battery voltage2. Support Bluetooth hands-free calls, built-in microphone, convenient and safe answering calls; caller ID3. Noise processing CVC during calls, wind noise suppression, full-duplex call technology;4. Support the A2DP function of mobile phones, and play high-quality mobile music directly after connecting to Bluetooth;5. Automatically connect back after turning on the power, and automatically enter the pairing state;6. Support TF card expansion to play MP3/WMA format music;7. It comes with a car charger with an output of 5V2100m, which can charge handheld terminal devices.8. AVX port output and input. Song name displayInstructions1. Boot up(1) Insert the device into the cigarette lighter power socket of the car, and it will automatically turn on after power on;(2) Select a transmitting frequency point on the device through adjustment;(3) Turn on the car audio and set it to FM radio, and adjust the receiving frequency of the car radio to be consistent with the transmitting frequency of the device.2. Adjust frequency and volume(1) This device supports full frequency point transmission, frequency range: 87.5MHz-108.0MHz. You can enter the frequency point adjustment mode by short pressing the frequency point option key, use the up and down direction keys to adjust to the desired transmission frequency, and then press the frequency point option key to confirm the frequency point.(2) Adjust the transmission volume: In music playback mode or call mode, long press the up and down direction keys to adjust the volume.(3) Song selection: You can short press the direction keys "" and "" to select the song you want to play;3. Play the music in the TF card(1) Insert the TF card into the TF card expansion slot of the device, and the device will automatically recognize and play the MP3/WMA music files in the TF card.(2) Play/pause: In the music playing state, short press the "" button to switch between music playing and pause.(3) Song selection: In the playback state, short press "" and "" to select the song.