1、Mode Switching: The input mode switch button can be used for USB or SD card mode and FM radio, easily switching between "mode" and "line input mode". 2、Bluetooth Connection: Press input to switch to USB or SD indicator HT or turn on the phone's Bluetooth, find Bluetooth "LDZS" and click to connect. 3、USB SD Card Mode: Insert the U disk or SD card, it will play automatically, you can use "Last song", "Next song" and "Pause Play" to control the playback. 4、Radio Mode: Press Input to switch to radio mode, then press the Play button, and the amplifier will automatically search for and save channels. 5、EQ Sound: Free to switch between a variety of built in sound effects according to your needs or preferences for the best listening experience.