Features: brand new and high quality Multiple audio input modes, Blutooth-compatible 5.0+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. AUX audio input, easy to achieve stereo playback sound. Simple appearance without exaggeration. Specifications: Material:ABS Model: YS-AP50L Transmission distance: 15 meter Power supply: DC12-24V Number of channels: left and right dual channel (stereo) Adapter speaker: 30W-200W 4 8 16 Size:Apporx. 52x52x22mm/2.04x2.04x0.86 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