Hardwired Ionization Smoke Alarm, With 9V Battery Back Up, 120V Wires Directly Into Your Home’s Electrical System, Ionization Smoke Sensor Reliably Detects Particles From Fast Flaming Fires, Gasket Less Mount System For Hassle Free Installation, Can Integrate With Up To 12 Other First Alert Or BRK Hardwired Smoke Detectors, , NOTE Please Check Your Local Building Code Requirements Before Installing This Product To Determine Compliance With Applicable Standards