Whether you use a motion sensor to trigger your alarm system or to turn on lights, it's important to install a device that will sense and respond quickly and accurately. The Force 2 40 x 40 Dual Tech PIR Motion Detector combines two proven motion detector technologies in one package, integrating PIR and microwave for accurate discrimination between intruders and potential false alarms. By comparing digital PIR and microwave signal analysis, the Force 2 40 x 40 Dual Tech PIR Motion Detector can eliminate false alarms common with single detectors. To prevent false alarms, both sensors must detect motion within a 10 second period of each other before any alarm is sent. For additional reliability and false alarm protection, the Force 2 40 x 40 Dual Tech PIR Motion Detector employs MOV transient/static protection, SMD construction for high RF immunity, protection from white light, and microcontroller low-voltage reset circuit. You'll appreciate the motion detector's adjustable microwave detection pattern to match your room size closely. Built-in temperature compensation is also included. If you have pets, it is advised that you instead install a Pet-Immune Motion Detector, which eliminates false alarms triggered by the movements of pets weighing up to 40 pounds.