Gentex 9123T Smoke Alarm, 120V Hardwired Interconnectable Photoelectric w/9V Battery Backup, T3 Horn & Integral Heat Alarm (917-0013-002) Available in 220VAC with 9VDC battery back-up Self-restoring 135&deg;F integral heat thermal Tandem up to 6 units Auxiliary Form A/Form C relay contacts Horn frequency 3100 Hz (nominal) Nominal 2.5% sensitivity Patented three position test switch Relays operate on battery back-up Quick-disconnect wiring harness 90dBA temporal 3 evacuation piezo horn 5-to-1 signal-to-noise ratio Pulsing LED sensing chamber Fully insect screened Interconnect with all Gentex tandem capable smoke alarms Easy Wash&tr