Sigtronics SPO-22N 2-Place High Noise Intercom Fail safe feature allows pilot to always hear radios - even if the intercom is off. Operates up to 40 hours on one 9-volt battery (included). Includes DC power cable to offer seamless operation on either battery or 11-34 Volt DC aircraft power. Radio priority assures that ATC hears only the crew member transmitting. Push to Talk Switch inputs for both pilot and copilot.