DESC: 120V, Commercial, AC Powered, Hardwire Smoke & Fire Alarm With Ionization Sensor & 9V Battery Back Up, Alarm Has A Test & Silence Button To Silence Nuisance Alarms, Green LED Light Under Test Button Indicates 120V Power, Red LED Light Indicates 9V Power, This Unit Usually Detects Fast Flaming Fires That Consume Combustible Materials Rapidly, Interconnectable Up To 12 Units, Fast Install Mounting Bracket Allows For Quick Connect For Most Electrical Boxes, Quick Connect Pigtail Locks Into Place For Fast Wiring, Box Pack Allows For Easy Display On Shelf Or On Deck Base Along With Wiring Materials, Unit Frequently Named In City & Suburban Building Codes By Model Number, Good For Sale In Oregon After New Revisions On Law #HB2586, 10 Year Limited Warranty, Replaces #4120SB .