The First Alert Battery-Operated Combination Photoelectric Smoke and Carbon Monoxide Alarm packs premium detection capabilities into a sleek, compact design. For those who want a reliable detection system without hiring an electrician or worrying about hardwiring, this battery-operated smoke and carbon monoxide detector is an ideal solution. The alarm comes equipped with a photoelectric sensor and a patented smoke entry system, allowing reliable detection of smoke produced by smoldering fires while keeping false alarms to a minimum. The unit also features an advanced electrochemical sensor that detects carbon monoxide leaks from multiple sources such as faulty fuel-burning appliances and blocked chimneys. This stylish smoke detector is sleekly designed to take up a fraction of the space of traditional smoke alarms, and it can be mounted unobtrusively on a wall or ceiling. A loud alarm sounds when smoke or CO is detected as well as a voice alert warning of the location and type of danger, and a convenient test/silence button lets you easily check whether the alarm is functioning and mute false alarms. Low profile compact round battery powered photoelectric smoke and CO combo alarm with silence feature. Tamper resistant, alarm locks to mounting bracket to prevent removal of battery and/or alarm. SpecificationsPower Type: BatterySensor Type: PhotoelectricElectrochemicalLow Battery Indicator: YesUL Listed: YesTest and or Reset Button: YesWeight: 1.0 lbs