Hardwired Smoke & Carbon Monoxide Detector With 9V Battery Back Up, Electrochemical Carbon Monoxide Sensing Technology As Well As Ionization Sensor That Detects The Fine Particles Of Fast Burning Fire, Indicator Lights On The Face Of The Unit Display The Presence Of Smoke Or Carbon Monoxide, 85 Decibel Siren, Can Connect To Other Compatible BRK & First Alert Detectors To Ensure All Alarms Will Sound When Threat Is Detected, Simple To Use With Single Test/Silence Button, Universal Mounting Brackets Makes Installation Easy, 7 Year Limited Warranty, NOTE: Please Check Your Local Building Code Requirements Before Installing This Product To Determine Compliance With Applicable Standards.