First Alert, 2 Pack, DC, Battery Operated, Carbon Monoxide Smoke Detector Combo Pack, Utilize Ionization Smoke Sensing Technology That’s Ideal In Identifying Flaming Fires, A Mute Button Has Been Included To Serve The Dual Purpose Of Silencing Nuisance Alarms Testing The Functionality Of Your Alarm, Featuring An Increased Nod To Safety With An 85 Decibel Sound Output, , NOTE Please Check Your Local Building Code Requirements Before Installing This Product To Determine Compliance With Applicable Standards