Excellent quality: high quality material, safe and durable. Classic appearance, increase the high-end experience of the rotary encoder, increase the mid-range adjustment, and fully cover the subwoofer, mid-range and treble sound effects. High fidelity: When used as an audio amplifier, the tone is warm and the fidelity is high. Wide range of uses: suitable for high quality and professional audio equipment, instruments, control circuits and telephone channel amplifiers. It has the characteristics of small size, high efficiency, high power and small heat. [Product Name] 2.1 Channel Bluetooth Audio Power Amplifier Board Module [Product Model]-AS21 [Number of channels] 2.1 channels (left channel + right channel + subwoofer) [Input ] AUX+Bluetooth+U disk+USB sound card (dial button to switch modes and ) [Bluetooth version]5.1 [Amplifier chip]TPA3255 [Voltage Gain]30dB [Switch mode]Mechanical switch (no need to wait for a long press) [Power supply by adapter]DC16~38V/ greater or equal to 10A [Adapted speakers] Left and right channels 30-220W, 3-8 ohmSubwoofer 30-350W, 2-8 ohm [Output power] Left and right channels less than or equal to 220W, subwoofer less than or equal to 350w [Protection mechanism] Anti-reverse connection, undervoltage, overheating, overcurrent short circuit protection (automatic recovery, no need to restart) Size: 141x131x27mm Tips: 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, 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! Colour: black Material: ABS Package Contents: 1 * Audio Amplifier Board Module 1 * Screwdriver Only the above package content, other products are not included. Note: Light 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.