Wireless motion sensor compatible with Ideal Security Skqh652 motion sensor alert set. Up to a TOTAL of 50 sensors can be linked to one receiver. Install one sensor at the front of your home or business and a second one at the back. Install one in your driveway and a second at your Garden shed. Many applications. Quick and easy to link to the receiver, one button to press on the receiver and a wave at the sensor and it's connected. Requires 3 aaa batteries (not included). can be installed indoors and outdoors. For outdoor applications try to shield from direct downpours. Batteries may freeze and signal is weakened in extreme cold temperatures.