The BRK Brands, Inc. model SC9120B is a wire-in, 120V AC 60Hz single and/ or multiple station smoke and CO alarm specifically designed for residential and institutional applications including sleeping rooms of hospitals, hotels, motels, dormitories and other multi-family dwellings as defined in standard NFPA 101. The SC9120B complies with UL217, UL2034, CSFM, NFPA 72, NFPA 720, HUD, FHA and other agencies that model their codes after the above agencies. They meet building codes where AC/DC with Silence smoke and CO alarms are required either separately or in combination. The alarms are interconnectable with up to 18 devices, of which 12 can be smoke alarms.