Multi hazard combo detects carbon monoxide, propane gas and natural/methane gas. Backlit digital display with test and silence. Covers only one wall outlet. Plug the alarm into a regular outlet, test, and it's ready. Battery back-up keeps alarm working ifelectricity fails. Point and click any remote control unit to quiet unwanted alarms (remote not included). With a line cord for high mounting to sense methane, low mounting for propane. End of life timer alarm chirps when it is time to replace, should bereplaced every 5 years for maximum protection. 85-decibel alarm. 3.1 in height x 5.6 in width x 2.1 in depth, 0.62 pounds. Meets UL1484 and UL2034 gas detector standards. Battery back-up, 9 volt battery included.