Simply plug the PowerOUT into any 120V outlet or power strip. When the power fails, the PowerOUT emits a pulsing alarm, about as loud as a conventional alarm clock. At the Same time, the PowerOUT illuminates three built-in, ultra-bright LEDs to provide safety lighting. The PowerOUT can be removed from the outlet and the three-position switch set to "LIGHT" position, silencing the alarm, and the ultra-bright LEDs will provide up to six hours of portable lighting.