Microwave PIR Motion Sensor – Microwave PIR Ceiling Mount Motion Sensors with time and lux level adjustments. This PIR Motion Sensor is a new type of Energy-Saving light control switch. It works by detecting heat rays emitted by the human body. Auto switching of lights or other fixtures based on human occupancy in residential and commercial buildings. Security systems for triggering of Buzzers or switching on Camera/DVR when human motion is detected.