Product : 1. There is no annoying sound during power-on, song cutting and pause; 2. Wide power supply : DC4.5-27V; 3. Two audio input modes: Bluetooth mode and LINE IN mode; 4. Two power supply interfaces: terminal block and DC2.1MM socket (compatible with most notebook power supply interfaces); 5. Power input anti-reverse connection function; Acrylic shell protection;Note: The power amplifier module does not contain power supply. It needs external power supply, and can also be connected to notebook power supply. Specifications: Product name: Bluetooth digital power amplifier board Model: -502B Power supply : DC4.5~27V Output power: 50W * 2 : 102dB Number of channels: two-channel stereo Product size: 87 x 53 x 29mm (with shell) Operating instructions: 1. Mode : The module has two modes: Bluetooth and LINE IN. When the Bluetooth power amplifier board is not plugged in the audio head, the Bluetooth mode is the default when powered on; When the power amplifier board is plugged in the audio head, the default mode of power-on is LINE IN audio line input mode; You can also switch modes by holding down the "PLAY/M" key. 2. Connect Bluetooth: When switching to the Bluetooth mode or the default Bluetooth mode is just powered on, the English "The bluetooth device is to pair" will be broadcast, indicating that the Bluetooth mode is entered and for pairing; the "XY" searched by the mobile phone Bluetooth_ BT "is the device name of the Bluetooth power amplifier board. Click Connect, and the Bluetooth power amplifier board prompts" The bluetooth device is connected successfully ", indicating that the power amplifier board is successfully connected to the mobile phone, and music can be played. Material: PCB+metal colour: blue Package Contents: 1 x -502B Bluetooth digital amplifier board 1 x Acrylic case Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.