2PCS Wireless PIR Motion Sensor Detector with Remote Control Security Alarm System Motion Sensor Alarm for Home Garage Alarm Alert Security Indoor Features: 1.Passive infrared sensor is an electronic sensor that can measure infrared (IR) light emitted by an object in its field of view. They are most commonly used in pirg-based motion detectors. 2.This motion sensor alarm is ideal to protect your property from unwelcome intruders. It can cover front doors, back doors, garages, sheds, outbuildings, etc., and can also be used for caravans and RVs. .