AUX+ Bluetooth audio input, HiFi sound quality, high fidelity, high-definition sound quality Subwoofer + left and right channel output External antenna available Four protection mechanisms: anti-reverse connection, overheating, overcurrent, short circuit protection Easily connect your audio system Product name: 2.1 channel Bluetooth audio amplifier module Product model: ZK-MT21 Input sensitivity: 500mV Power amplifier chip: domestic power amplifier chip Bluetooth version: 5.0 (unobstructed, 15 meters) Input method: AUX+Bluetooth Number of channels: 2.1 channels Protection mechanism: Anti-reverse connection, overheating, overcurrent, short circuit protection Compatible speakers: 20~100W, 4~8Q Adaptable power supply: DC 12~24V/5A or above (24V battery pack cannot be connected) Output power: left and right channels Less than 50W, subwoofer Less than 100w Tip: Only when the audio input is sufficient and the power supply voltage/current is sufficient, there will 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 ensure that the power of the adapted power supply is greater than the actual working power of the amplifier Colour:Black Material:PCB Package Contents: 1 x Upper Cover Plate 1 x Lower Cover Plate 1 x PCB Plate 1 x Screwdriver 1 x Power Adapter 5 x Buttons 4 x M2x16 Copper Posts 8 x M2x3mm Screws 4 x M2x3+3 Copper Posts 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.