Use this motion sensor to protect locations where door/window sensors are impractical or not needed. For example, use a motion sensor to protect large areas or open floor plans. Motion sensors also provide backup protection for door/window sensors. The Pet Immune SAW PIR Motion detector utilizes advanced signal processing, a new custom designed lens, and a new custom designed sensing element. The combination of these improvements provides false alarm immunity for pets with a combined weight of up to 40 pounds (18 kg) while still providing superior human catch performance.