The Hub is the brain of the system. It communicates wirelessly with your security and home automation devices and enables you to monitor and control your system via the mobile app.
We recommend that you put a sensor on every door that leads into the property. And on every window that can be used by an intruder. Those easy-to-install, wireless sensors will notify the Hub when the door/window is opened. If the system is armed, this will trigger the alarm.
A Motion Detector helps secure an area by detecting and reporting human motion in that area. An Indoor Motion Detector is a useful second line of defense to confirm intrusion after a door or window sensor is triggered. And is essential if you have entry points that are not protectd by sensors.