690MBX-Heat-Alarm-Mains-Powered-with-Battery-Backup-BRK-690MBX-p-The-BRK-reg-690MBX-Heat-Alarm-is-mains-powered-with-a-9V-alkaline-battery-back-up-that-will-provide-power-to-the-unit-in-the-event-of-a-mains-failure-It-features-Class-A2-Thermistor-sensing-technology-making-it-ideal-for-use-in-the-kitchen-garage-or-attic-p-p-This-alarm-features-a-test-button-&-will-also-notify-you-in-the-event-of-a-low-battery-With-LED-operating-indicators-&-an-alarm-source-indicator-It-can-be