The CS-4 is an 4 Channel automatic microphone mixer. Full feature design includes : Daisy-chain with unlimited numbers of the mixer. Three operation modes: one-channel-at-a time, all active or override. Switchable inputs accept microphones or line level devices .Switchable output levels between mic. and line level. Individual gain control and phantom power for each channel. Last In stays on for continuous ambience sound. Control voltage provided to trigger external device such as speaker switching and camera switching