This is a 12-24V DC single power supply, using TI's TPA3116D2 high-performance digital power amplifier chip as the core, one for the parallel bridge bass channel power amplifier output, one for the left and right channel power amplifier output. Can support 100W (bass channel) + 50W (left channel) + 50W (right channel) three-channel output.     Support Bluetooth audio receiving, external audio source input interface, with preamplification, bass frequency division processing; bass volume, bass frequency, left and right channel volume, treble, function control switch / total volume, 5 adjustment potentiometers.     Wide operating voltage, power-saving design, efficiency up to 90%. Can use a good switching power supply, notebook computer switching power supply, can also use a charging bottle, or car power supply, etc.     New Version: Bluetooth 5.0     Operating voltage range: DC 11-25V (current 3-4A, or 19-24V / 4-5A, such as high power requirements 20-24V / 8-9A above)     Note that the DC no-load voltage should not be greater than 25.5V.     Bluetooth receiving distance:Greater than 8 m (meters)     Audio input sensitivity: 600-800mV     Frequency response range: 20Hz-20KHz     Speaker impedance: left and right channel speakers: 4-8 ohm     bass speaker impedance: 2-8 ohm     The output power is related to the supply voltage/current, the speaker impedance, and the size of the audio input. When the power supply voltage/current is sufficient, usually the power supply voltage is higher and the relative output power can be made larger. Speakers with different impedances have different output powers. Usually, the speaker impedance is smaller and the power is easier to achieve.     Function switch Instructions for use:     1. Plug in the power on default Bluetooth mode     2. Bluetooth disconnected, long press the switch can switch to the audio input mode     3. Bluetooth play status, short press the switch to pause / play     type: A/B     Colour:blue + silver     Material:Plastic + Metal + Electronic Accessories          Package Contents:     1 x TPA311     3. Bluetooth play status, short press the switch to pause / play     type: A     Colour:blue + silver     Material:Plastic + Metal + Electronic Accessories          Package Contents:     1 x TPA3116D2 Bluetooth 5.0 Subwoofer Amplifier Board     1 x connecting wire     5 x knob caps (random colors, don't accept the specified color)      1 set x screw studs     Note: Different batches, the color of the electronic accessories on the power amplifier board is random, does not affect,DIY parts, need to assemble          Only the above package content, other products are not included.     Note: Light shooting 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.