TX-E721 Wireless Pet-Immune Motion SensorTX-E721 Passive Infrared (PIR) Motion Detection Sensor is a wireless, battery-powered device that provides outstanding performance. Featuring advanced signal processing, this detection device is capable of eliminating false alarms caused by pets weighing up to 40 pounds. Well suited for both homes and small to mid-sized businesses, the motion detector identifies the movement of a person within a specific area by sensing the infrared energy emitted from a body as it moves across the sensor’s field of view. When this motion is detected, the sensor transmits an alarm signal to the control panel.