The BRK model no. 3120B is a wire-in 120 V AC 60 Hz single and/or multiple station photoelectric and ionization dual sensor 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 nape 101. Model 3120B complies with UL217 CSFM nape 72 HUD fa and other agencies that model their codes after the above agencies. It meets building codes where AC/DC photoelectric and ionization combination smoke alarms are required. The BRK 3120B is a state-of-the-art hardwired with battery backup smoke alarm that features dual photoelectric and ionization smoke sensing technologies. This alarm features two latching features and two silence features. Alarm latch: easily identifies initiating alarm even after alarm condition has subsided. Low battery latch: identifies which unit is in low battery condition by blinking the green power light. Low battery silence: temporarily silence the low battery chirp for up to eight hours. Alarm silence: silence alarm for several minutes. Other features include an 85 dB horn single button test/silence an easy access battery drawer and dust cover. Optipath 360 technology: exclusive patented technology provides 360 degrees of direct access to the smoke sensor. Two locking features are provided to prevent battery theft and/or theft of the unit. Connection to AC power is made with a quick-connect wiring harness. Installation is quick easy and cost effective.