The AQSESS ACRX-PIR is a Request to Exit Motion Detector. It allows for a "hands-free"exit option when exiting a door that has access control. The sensor detects when a person is walking up to the door and and release the door lock automatically. It differentiates between person and electrical interference or even light. You can mount this exit sensor to the door frame, the wall or ceiling and it can be set from .25 to 60 seconds of hold time. Accepts 12 to 24 VAC/VDC.