Product Feature: 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: ZK-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: TPA3251D2 Adapter speakers: left and right channels 30-220W, 3-8Ω subwoofer 30-350W 2-8Ω Output power: left and right channels ≤ 220w subwoofer ≤ 350W Adapter power supply: DC 12~38v, ≥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 press and wait) Voltage gain: 30dB Product weight: net weight 346g, including packaging 408g Product size: 141*131*27mm Tip: Only when the audio signal input is large enough and the power supply voltage/current is large enough, will 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 greater than the actual working power of the power amplifier! Package list: 1pc of 2.1 channel TPA3251 Bluetooth digital power amplifier board module