This is a Double pointer VU meters with drive boards For 5W-50W amplifiers .The Power Supply Input is For The Backlight DC/AC 5-12V ＞0.1A;R1 And R2 Adjustable Resistance for Adjust Pointer jump;Notice :The Connect cable need you welding on the Driver board Debugging method:Method 1: Connect the power amplifier with the signal generator 1KHZ signal, adjust the volume of the power amplifier to the maximum, adjust the adjustable resistance, so that the meter pointer points to the 0 position Method 2: No signal generator, you can use Android mobile phone to download the signal generator software, use the mobile phone to output 1KHZ signal to the power amplifier, adjust the power amplifier volume to the maximum, adjust the adjustable resistance, so that the meter pointer points to the 0 position Color: As Shown Material: plastic Package Contents: 1* VU Meter,1*Stereo Audio Amplifier Board Only the above package content, other products are not included. Note: Light reflection 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.