Design: No power supply design, can be directly inserted and used, no input and output signal loss, switch transmission. Two adjustment methods: 1. by gain adjustment, 2. by frequency adjustment. Usage: mainly used to select common output devices and switch various stereo signal inputs. If there are two stereo signal sources (such as TV audio, MP3 player, CD player, video game, mobile phone, tablet, computer, recorder), the device needs to output to the power amplifier or active speakers. Stereo source switcher: Two sets of stereo source switchers solve the complicated line blocking operation. As long as the required input device signal source is uniformly connected to the switch, it can be easily . interface: The input and output standard adopts interface design, and the switch adopts accurate 2-position manual button switch. Type: auto power amplifier. Voltage: 12v. Frequency: 150Hz - 40Hz. Gain: 0db to -12db. Color: Black Material: ABS Package Contents: 1 x Car Audio Amplifier 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.