Pet-immune motion detector combines microvwave with PIR for maximum reliability. Install motion sensors that not only sense movement but also distinguish the difference between the motion of a human body and any other disturbance to help eliminate false alarms. The 85-Lb. Pet-Immune Dual-Technology Digital Detector combines a passive infrared (PIR) motion detector with a complementary active microwave sensor in a single unit for an accurate, false alarm-immune motion detector for maximum reliability. Ideal for use in residential and light commercial environments, the 85-Lb. Pet-Immune Dual-Technology Digital Detector won't be fooled by your pets and even allows easy customization for room size: When it's being installed, you can select the area to be secured from 20 to 40 feet. The 85-Lb. Pet-Immune Dual-Technology Digital Detector implements a variety of patented technologies, including FM Digital Signal Processing (FM-DSP), which adjusts automatically based upon the room size selected, thus optimizing both PIR and microwave performance within the protected area. The PIR motion detector employs a cylindrical lens with uniform detection sensitivity beginning at 1.8 feet (0.5m) away from the detector up to a distance of 40 feet (12m). True Motion RecognitionTM with Fuzzy Logic algorithm (TMRTM) allows the motion detector to distinguish between the true motion of an intruder and any other disturbances, which cause false alarms. An on-board motion event jumper determines whether 1 or 2 consecutive motion events will trigger an alarm to your security system. Additional features include a test input that permits switching the detector to the walk test mode remotely without removing the front cover. This motion detector is safe for use in homes with pets up to 85 pounds. more info