Line Mixer with 4 Channels. Individual Level Controls. Compact Design. Ultra low Noise Operation. Powered via 9 Volt Power Supply (supplied) or PP3 Battery (sold separately). This 4 channel line level mixer is designed to mix down 4 mono line level signals- suitable for use where you may be running short on mixer channels. The four inputs and one output are via 1/4" mono jack plugs- each input has its own level control. The mixer can be powered by either the supplied power supply or a PP3 battery (sold separately) making this mixer very portable. There is a master volume control which doubles as an on/off switch. The peak light stays on to show there is power to the mixer via power supply or battery. The peak light flashes more boldly as the input signal increases.