* Plugs into standard outlet; no batteries * 120 volt; AC 60 Hz power;uses 40% less power * Samples air once every second * Calibrated at four levels for accuracy * Silencer button; re-alarms if levels persist * Unique self testing system alerts if malfunctions * 3 indicator lights: green power status; yellow service; red warning * Covers only one outlet * 5 year limited manufacturer's warranty