Computer rooms, lab doors, retail stock rooms, offices, storage rooms, locker rooms, and entrance ways with single door openings account for a number of the locations where you would expect to see the Detex EAX-300 battery powered door propped alarm. Using the Detex EAX-300 propped door alarm is like having an official ready to throw the flag when one of your secured doors is held open or propped open past the legal time limit. You get to determine how long that time is before the alarm goes off. It can be from 1 second for situations where a door should never be left open, to 4 minutes, where people are accessing the area many times during the course of a day or week, and you don't want to irritate them with the alarm when they aren't doing anything wrong to begin with. One other thing to like about this security door hardware is the EAX300 automatically silences itself when the door closes, saving you or the key holder from making a trip to turn it off.  Requires  (sold separate) for arm/disarm control.