This is a product that uses a DC single power supply of 9-24V, uses TPA3116D2 high-performance digital power amplifier chip as the core, parallel bridge connection, bass channel power amplification, and supports 100W (bass channel) output. External audio source input interface, with pre-amplification, bass crossover processing; bass volume, bass frequency, switch/master volume, 2 adjustment potentiometers. DC9-24V wide operating voltage, power-saving design, efficiency as high as over 90%. You can use switching power supplies with good performance, laptop switching power supplies; you can also use charging bottles, or car power supplies, etc. The board is a finished board that has been welded and tested. Connect the speaker box according to the diagram, connect the appropriate power supply, and correctly connect the audio source input, and it is ready to use. note: Depending on the batch, the electronic components on the amplifier board may be different from the pictures, but the functions are the same and do not affect use. Material: PCB+electronic components+metal colour: Black Package Contents: 1 x Power Amplifier Board 1 set accessories (accessories color random, Cannot be chosen the specific color.) 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 picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.