Features:4-IN 4-OUT (switch audio sources input)(1) Switch different input or output conveniently(2) No need power supply, plug and play directly(3) Circuit design does not affect sound quality(4) Made of FR4 PCB circuit board(4) Mini size compact audio splitter for home audioApplications:Connect sockets are AUX 1/8" (3.5mm)Input connections: Computer / Phone / Music player. etc.Output connections: Active speaker / Headphone amp / Power Amplifier. etc.Use instruction:Left knob on top: for switch/select input signal wayRight knob on top: for switch/select output signal way