USB: Connect to U disk (maximum support 32GB) TF: Connect to TF memory card (maximum support 32GB) AUX: Audio Input Interface VOL-: Short is the last song; Long is the volume reduction. PLAY/PAUSE: Short is the switch between pause and playback; Long is the radio FM automatic station. VOL+: Short is to choose song; Long is to increase the volume. MODE: Switchover of USB/TF/FM/LINE IN/BLUETOOTH Voice Main control IC: AC5322B Bluetooth IC: AC5322B Bluetooth version is version 5.0 Music format: MP3/WMA/WAV/FLAC/APE lossless format music Power: 2 * 3W, connected to two 3W speakers Radio FM Frequency: 87.5-107.5 MHZ Introduction of Support Functions: Support MP3/USB/TF/LINE IN/FM/BLUETOOTH/Remote Control/DC 5V About structure: panel size: 107 * 25 MM, panel corner and screw hole position, then cover , the depth of the board is 32 MM Description of recording function 1. the MODE button for a long time to start recording, and then the MODE button for a long time to cancel recording function. 2. the PLAY/PAUSE key to play the recording file. 3. When recording, it is more necessary to connect a storage device, such as a U disk or a TF card. Colour: Black material: plastic Package Contents: 5 * Bluetooth 5.0 DC 5V Amplifier Decoder Board 20 * Cable 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.