About the BRK Smoke Detectors and BRK RM4 Smoke Alarm Accessory RelayThe BRK RM4 is a relay device that is designed to work with your detection system to allow for interconnectivety with bells, sirens, emergency strobe lights, exhaust fans, and other devices. The BRK RM4 allows for a more complete alarm system, especially in larger buildings where a bell or siren may be needed to alert residents. The BRK RM4 now works with BRK#39;s "Smart Interconnect" Carbon Monoxide alarms. The RM4 is very easy to connect, using the formC contacts, once the alarm system sounds, the devices connected tothe RM4 will automatically turn on. Connected devices will turn off once the alarm is off. The BRK RM4 is UL listed (UL317, UL2034, UL539)Additional Information :