Smoke Alarm, Battery Chemistry Alkaline, Battery Location Side, Battery Locking Pin Yes, Battery Size AA, Communication Protocol Wireless, Compatible With BRK Hardwired Alarms, BRK Wireless Interconnect Alarms, Detector Type Smoke Detector, Features Bridge Unit-Wireless & Hardwired Photoelectric 120-Volt AC/DC Smoke Alarm, 10 year limited warranty, 915MHz with 65K security codes and 3 channel hopping, Includes (2) AA Batteries, Number of Tandem Detectors 18, Power Source Hardwired