A Motion Sensor alerts you any time it detects motion. A MotionViewer does the same, plus it has a built-in camera that captures a 10-second video clip so you can watch what happened. The video is transmitted over Honeywell’s Secure Wiselink Protocol for safekeeping. Both Motion Sensors and MotionViewers work by detecting heat to eliminate false alerts from curtains blowing in wind, moving ceiling fans, or even small pets. They are totally wireless and designed to last a long time so you don’t have to service them regularly.