Use of TDA7388 digital amplifier chip as the core. outlook and welding points. and good performance, low noise and distortion. REM terminal: high level is effective, connect the REM terminal for car use. For general application or DIY use, directly connect the positive pole of power supply, otherwise there will be no sound Line inputs 1 and 2 are , suitable for four-channel mode, each channel works independently; All switches are in the ON position, it is the 2-channel input 4-channel output mode; The two left and right channels output the same sound, equivalent to widening the stereo mode of the sound field. Compatible Audio & Video Equipment Style: Amplifier Chip type: TDA7388 x 1 Input voltage: DC 12-18v Output power: 4x41W, 4ohm Max. Channel: four channel surround sound Output impedance: 4-8ohm Frequency response: 20hz-20khz Speaker Recommendation: each channel 3-6.5 inch; 4-8ohm; within 50W colour:Red Material:Plastic + Metal size:76 x 58mm Package Contents: 1 amplifier board Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real . The measurement allowed is +/- 1-3cm.