1: Wide range of applications 2: The appearance is simple and beautiful 3: APP has comprehensive functions 4: Real stepless tuning, not digital multi-stage grading adjustment. 5: The mechanical switch can be turned off with one turn, no need to wait for a long time, which is convenient and fast. Product name: 2.1 channel bluetooth audio power amplifier module Product Model: -AS21 Number of channels: 2.1 channels (left channel + right channel + subwoofer) Input method: AUX+Bluetooth+U disk+USB sound card (dial button to switch modes and songs) Bluetooth version: 5.1 Power amplifier chip: TPA3255 Adapter speakers: left and right channels 30-220W, 3-8; subwoofer 30-350W 2-8 Output power: left and right channels 220w; subwoofer 350W Adapter power supply: DC 16-38V, 10A Protection mechanism: anti-reverse connection, undervoltage, overheating, overcurrent, short circuit protection (automatic recovery, no need to restart) Switch mode: mechanical switch (no need to long and wait) Voltage gain: 30dB Tip: Only when the audio signal input is large enough and the power supply voltage/current is large enough, there be enough output power! The higher the power supply voltage, the greater the output power, and the smaller the speaker impedance, the greater the output power! Please make sure that the power of the adapted power supply is the actual working power of the power amplifier! Note: The shell needs to be installed by yourself. Color: Black Material: Metal Package Contents: 1 x Amplifier Board 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.