interfaces, multi-functional and strong compatibility.AUX audio connection adjustment of left and right channel treble and /subwoofer adjustment 360-degree stepless tuning.Volume adjustment: high-end encoder knob adjustment, smooth feelProtection mechanism: overvoltage, undervoltage, overheating, clipping, short circuit, etc.Unique function: support Audio-APP controlProduct name: 2.1 channel bluetooth audio amplifier boardProduct : -S350HBluetooth version: 5.1Signal-to-noise : 92dBFrequency range: 20Hz-20KHz supply: DC18-38V/10A or more audioChannel: 2.1 channelAudio output: left and right channels + subwooferAudio input: Bluetooth+AUX+U disk+USB sound cardOutput : 220W*2 (left and right channels) + 350W (subwoofer)Left and right channel maximum output : 220W/3Q2--36VDC 175W/4Q2--36VDC 100W/8Q2--36VDCSubwoofer maximum output : 355W/2Q--36VDC 250W/3Q--36VDC 195W/4Q--36VDCSubwoofer (subwoofer) compatible speaker: 20W-200W/2Q-8QProduct size: 133 x 130 x 25mmMaterial: PCBcolour: blackPackage Contents:1 x Top cover plate1 x Bottom cover plate1 x PCB board1 x screwdriver4 x M2x18 copper pillar4 x M2x4+3 copper pillar5 x button cap8 x M2x3mm screwsOnly the above package content, other products are not included.Note: Light reflection and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.