The Kidde SM120X can be used to activate auxiliary warning devices such as external bells and sirens, hallway or stairway lighting. This relay will only activate when it receives a smoke signal from an interconnect Smoke Alarm.This module is only activated by a smoke alarm interconnect signal. The relay portion of this module can be used to activate auxiliary warning devices such as external bells and sirens, hallway or stairwell lighting. It provides isolated, (no internal connection to 120 volts AC) normally open, and normally closed contacts. The power supply portion can be used to connect spot type heat detectors (Rate of rise or combined rate of rise and fixed temperature only) and manual pull stations with interconnected multiple station alarms.