an emergency exit device of the push bar type to control entry and exit of personnel , including a crossbar which may be pushed toward a door to actuate mechanisms which retract a latch bolt , and an alarm and key system for selective alarm actuation . the alarm and key system includes internal control mechanisms which are mounted in a tamper - proof housing , which may be accessed only by operating the push bar and actuating the alarm . a light emitting diode in the alarm assembly indicates alarm state , the presence of power , and a preset delay interval for alarm actuation . a variety of internal and external key operation configurations may be employed . a fastening arrangement for the exit device housing provides security against unauthorized manipulation of alarm components . where mounting the alarm assembly within the exit device frame , an internal mounted guard member may include a protection flange to block access to the alarm .