PLS-4 is a four-channel Line Switcher. You can use an extensional footswitch pedal to select one of the four channels. For example, plug the guitar to the INPUT, send the sound to 4 different amplifiers, and select one of the amplifiers. Or, input 4 audio devices to PLS-4 and select one of them to output. 1.1 input to 4 outputs, or 4 inputs to 1 output 2.Remote footswitch pedal (optional) 3.True-bypass 4.Extra Low Noise 5.Mute Function