Features: No power supply design, can be directly inserted and used, no input and output signal loss, switch transmission. Two adjustment methods: 1. by gains 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 stereo, MP3 player, video game, mobile phone, tablet, computer, recorder), the device needs to output to the power amplifier or active speakers. Two sets of stereo source switchers solve the complicated line blocking operating. As long as the required input device signal source is uniformly connected to the switch, it can be easily selected. The input and output standard adopts interface design, and the switch adopts accurate 2-position manual button switch. Specifications: Material:ABS Voltages: 12V Frequency: 150Hz-40Hz. Gains: 0db to -12db Note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual color of the item. Package includes: 1Piece Bass Control Knob