Protect your family with the Kidde Firex Carbon Monoxide, Propane, Natural and Explosive Gas Detector, Hardwired with Battery Backup. The easy to install electrochemical Kidde Firex Carbon Monoxide, Propane, Natural and Explosive Gas Detector, operates by plugging the carbon monoxide alarm into a typical wall outlet. A 9-volt alkaline battery provides backup during power outages. Using electrochemical sensor technology, the Kidde Firex Carbon Monoxide, Propane, Natural and Explosive Gas Detector alerts to poisonous, invisible, combustible gases. The Kidde Firex Carbon Monoxide, Propane, Natural and Explosive Gas Detector has 3 LED lights that indicate: power connection, if the alarm senses combustion, fire, or smoke, or if the alarm is activated. The display will have a red dot in the lower, right corner that will blink to indicate normal operation. The gas alarm includes a test button that will electronically simulate the presence of CO or gas when pushed. When the unit detects carbon monoxide the alarm pattern will be 4 quick beeps and show in the display the carbon monoxide concentration in Parts Per Million. When the unit detects gas, the word "GAS" will be displayed and an alarm will sound. UL Certified with a 5-year limited warranty. Meets requirements of UL 2034.