Feature This circuit can be used when the sound of your device is small when connected to the power amplifier. It is suitable for small audio signal amplification, the amplification factor is 10 times (20db), and the front 3.5mm interface can be connected to headphones; Power supply: DC9-19V The amplifier chip is a dual op amp NE5532 Input and output are 3.5mm headphone jack or RCA Size: 87 x 50 x 37MM Colour: Black material: plastic Package Contents: 1 x Audio Switch Switcher 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.