All Sentrol Series 2700 triple balanced high security magnetic contacts have a "Dead Space" 0.0 inches to roughly 0.2 inches from the switch face. That means the Actuator Magnet can never be mounted closer than this for proper operation. The Defeat Key fits into this space and makes the switch think it sees the actuator magnet in the secure position.

If the Defeat Key is inserted while the door is closed, nothing happens. There are no false alarms during insertion. The door may be opened without incident as the switch is always in the secure state.

If the Defeat Key is applied while the door is open, the electronic security monitoring system registers a closed door indicating a secure state and maintains that status whether or not the door is open or closed.