The BRK Brands, Inc. model number 9120B is a wire-in, 120V AC 60Hz single and/ or multiple station smoke 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 9120B complies with UL217, CSFM, NFPA 72, HUD, FHA and other agencies that model their codes after the above agencies. It meets building codes where AC/DC with Silence smoke alarms are required. The alarms are interconnectable with up to 18 devices, of which 12 can be smoke alarms. The BRK® 9120B alarm features a dual ionization smoke sensing chamber, an 85dB horn, 9V battery backup and a "silence" feature. The "Smart Technology" system is designed to reduce nuisance alarms. "Latching Alarm Indication" remembers which unit initiated an alarm. When interconnected in a series, the unit that triggered the alarm rapidly flashes its red LED indicator. After the alarm condition subsides, the initiating unit will store in memory or "latch" the information and begin to flash the LED indicator 2 seconds on, 2 seconds off. The "Perfect Mount" system features a gasketless base and a mounting bracket that keeps the alarm secure over a wide rotation range to allow for true alignment. Other Contractor Preferred features include a dust cover to keep alarm clean during construction, keyhole slots in the mounting bracket eliminate the need to remove the electrical box screws for installation. Two locking features are provided to prevent battery theft and/or theft of the unit. Connection to AC power is made with a "QuickConnect" wiring harness. Installation is quick, easy and cost effective.