The Kidde Carbon Monoxide Detector, Propane, Natural, & Explosive Gas Alarm, Plug-In Wall with 9-Volt Battery Backup, Digital LED Display uses electrochemical sensor technology to detect poisonous carbon monoxide, methane gas, sewer gas, propane gas or natural gas in your home and alerts you by sounding an 85-decibel alarm & displaying the amount of carbon monoxide detected or stating "gas" on the digital display when detecting explosive gas. Setup is easy as the Kidde carbon monoxide alarm plugs into a standard, 120V AC power outlet in your home, while a 9-volt alkaline battery (included) works as a backup in the event of a power failure. When carbon monoxide is detected, the digital display shows the level of carbon monoxide the alarm is sensing and updates every 15 seconds. Peak Level Memory records the last time carbon monoxide was detected or when the unit was tested. The Smart-Hush button silences the unit for approximately 8 minutes, which is helpful when this smoke detector carbon monoxide detector combo sounds from things like routine cooking or shower steam. Extension cord (included) allows for placement on a table or shelf. Install a carbon monoxide detector on every level of your home and near bedrooms to keep your family safe. UL certified with a 6-year warranty. Meets UL 2034 and UL 1484.