Features: brand new and high quality Multiple audio input modes, Blutooth-compatible 5.1+AUX+USB flash disk+USB sound card. Mechanical volume knob, turn the knob to switch the machine on and off, no need to press and wait to see the indicator light. True stepless tuning. The higher the power supply voltage, the greater the output power, the smaller the speaker impedance, and the greater the output power. The product is designed with two tpa3255 power amplifier chips, with ultra-low distortion and high-definition sound quality. Simple appearance without exaggeration. Specifications: Material:ABS Model: YS-AS21 Amplifier Chip: TPA3255 Channels: 2.1 channel (left channel+right channel+subwoofer) Audio Input: AUX+BT+USB disk+USB sound card Adaptive Power supply: DC18-38 V ,10A Adapter Speaker: L&R channels 30-220W,3-8 Subwoofer30-350W,2-8 Output power: R&L channel220W, subwoofer350W Voltage gain: 30dB Size:Approx. 141x131x27mm/5.55x5.15x1.06 inches Note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1x Power Amplifier Board