• The front cover design of the alarm may vary but product function remains the same.
• Help keep your family safe with this hardwired smoke alarm that wirelessly interconnects with other First Alert–enabled alarms to create a home safety network.
• Equipped with photoelectric smoke sensor optimized to detect larger smoke particles produced by smoldering fires; helps minimize the number of false alarms.
• Wirelessly connect up to 18 First Alert enabled alarms for the maximum in whole-home protection.
• Hardwired alarm includes 2 AA backup batteries for continued monitoring in the event of a power outage.
• Includes test/silence button, low-battery warning, EZ access battery door.
• First Alert has been the most trusted brand in home safety since launching the first residential smoke alarm in 1958 (Based on a First Alert Brand Trust Survey in February 2018).

Product Description ------------------- The First Alert SA520 Interconnected Smoke Alarm with Hardwire Adapter Included allows you to create an interconnected fire alarm system without the hassle of wiring. Use this smoke detector to replace an existing hardwired smoke alarm and then install additional First Alert wireless alarms for an interconnected safety network (additional detectors sold separately). This hardwired smoke and fire detector can connect and communicate with up to 18 compatible alarms, so when one alarm is triggered, the entire system will sound. Equipped with battery backup, this smoke and fire alarm allows for protection during power outages. When one alarm is triggered, all connected alarms will sound Integrated battery backup allows continuous detection during power outages Hardwired smoke alarm can communicate wirelessly with other compatible alarms to create a fire alarm system (additional alarms sold separately) Create an Interconnected Fire Safety System The First Alert Interconnected Smoke Alarm with Hardwire Adapter Included makes it easy to begin creating a safety network of detection. This detector is designed to replace an existing hardwired 120-volt alarm so you can add up to 18 First Alert wireless interconnected alarms By connecting multiple wireless interconnected detectors, you can be alerted to danger on the other side of your house before the smoke from that area reaches you. When one alarm sounds, all connected alarms in the system will sound simultaneously. Hardwired Smoke Alarm The smoke detector is designed to easily replace most existing 120-volt hardwired alarms. Equipped with an easy adapter plug, there is no need to rewire when installing the fire alarm. Also, in case of power outages, the smoke detector has a battery backup feature designed to ensure continuous protection. A low-battery light and chirp will let you know when the AA batteries need to be replaced in the smoke detector. Model SA520 Product Type Smoke Alarm Sensor Type Photoelectric Power Supply Hardwired Includes Hardwire Adaptor Plug Battery Backup Yes Backup Battery Size AA Wireless Interconnectivity Yes Product Height 2 in Product Length 5 in Product Width 5 in Product Weight 1 lb UPC Number 029054002440 Warranty 10 Years Limited .com ---- "The First Alert SA521CN-3ST (Model SA520B) Wireless Interconnect Integrated Smoke Alarm links the alarms throughout your home. This 120VAC hardwired wireless detector with battery backup integrates single alarms into a system. By adding Wireless Interconnect battery powered alarms elsewhere, when one alarm sounds, all alarms will be notified. Easily link alarms with the press of a button. The RF Interconnect technology continues to provide a reliable and secure radio frequency communication between Wireless Interconnect alarms. This technology features 915 MHz frequency with 65,000 security codes, and three (3) channel frequency hopping. The unit is compatible with an assortment of First Alert wireless alarms, which includes the SA501CN-3ST (SA501B), SA501CN2-3ST (SA501B2), SA511B, SA511CN2-3ST, SA520B, SA521CN-3ST, CO511B. SCO501CN-3ST (SCO500B), SCO501CN2-3ST. Photoelectric smoke sensor reduces nuisance alarms. Easy access battery drawer: no need to remove an alarm from the ceiling to change battery. Includes 10-year limited warranty. Meets UL standards. Note: This product is intended for non-professional do it yourself installation. If you would like information about a professionally installed and monitored system, please contact First Alert Professional at 1-800-921-6025. First Alert Professional is not affiliated with BRK Brands, Inc. "