ART Phantom II Pro XLR connectors for balanced inputs and outputsLow-power, high-efficiency CMOS circuitry for long battery life using a standard 9-Volt battery (Alkaline recommended)Can be powered with an external power supply from AC mainsRugged extruded aluminum case with accessible battery compartmentLED lighted On/Off switchLow-noise, low-distortion circuitry It provides clean, reliable phantom power for one or two condenser microphones in a rugged, compact, and portable power supply unit Innovative low-power circuitry generates the higher voltage necessary for powering microphones while maximizing battery life The Phantom II Pro phantom power supply installs inline between your microphone and a balanced line input on your gear Balanced lines offer increased immunity to external electrical noise, such as hum