491 SDC "Break Glass" Emergency Door Release with Siren, 1-Gang, Blue, DPDT, 10 Amp. The SDC 491 Emergency Door Release 'Break Glass' Station provides immediate unlocking of perimeter doors or interior doors that are equipped with fail-safe electric locks. The 491’s built in alarm may be used as a local door annunciator. The SDC 491 is specifically designed for emergency door release and may influence the approval of an electric locking system. This type of Emergency Door Release may be preferred over a pull station since greater commitment is required to break the glass. Aluminum rod for striking the glass is included. (Not required to break the glass). Blue 'Break Glass' station, emergency door release, 2-SPDT 10 Amp contacts with built-in local alarm (12/24V), Single gang box mounted.