First Alert Hardwired Wireless Smoke Alarm with Photoelectric Sensor and Battery Backup, SA521CN-3ST

"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. "

• First Alert Smoke Detector Alarm | Battery Powered with Wireless Interconnect | 2-Pack, SA511CN2-3ST
• First Alert Wireless Interconnected Photoelectric Smoke and Carbon Monoxide Combo Alarm with Voice and Location, SCO500B
• First Alert CO511B Wireless Interconnected Carbon Monoxide Alarm with Voice and Location
• First Alert SCO500B (Series SCO500) ONELINK Battery Operated Combination Smoke and Carbon Monoxide Alarm with Voice Location *2-Pack*
• First Alert Wireless Battery Operated Smoke & Carbon Monoxide Alarm (2 Pack)
• First Alert Hardwired Talking Photoelectric Smoke and Carbon Monoxide Detector, BRK SC7010BV
• BRK Brands HD6135FB Hardwire Heat Alarm with Battery Backup
• First Alert Smoke Detector, Photoelectric and Ionized Alarm | Hardwired with Battery Backup, BRK 3120B
• Onelink Smoke Detector and Carbon Monoxide Detector | Hardwired | First Alert
• First Alert SCO500B Interconnected Wireless Battery Combination Smoke CO Voice 6 pack