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, 10 Year Limited Warranty, NOTE: Please Check Your Local Building Code Requirements Before Installing This Product To Determine Compliance With Applicable Standards.