Features 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. Specification Item Type: Car Amplifier Material: Aluminium alloy Input Voltage: 12V Output Power: 20W x 4 Frequency Response: 20HZ-20KHZ Harmonic Distortion: 1KHZ 0.055% 4W SNR:>86db High Pitch Control: 10KHZ± 12db 220mv 47K Power On Control: 100HZ± 12db 220mv 47K Card Reader: SD/USB Format: MP3, Bluetooth Remote Control Battery Specifications: 1 x CR1220 (not included) Package List 1 x Car Amplifier 1 x Manual 1 x Remote Control