Expand your AAA+ Home Smart Center home security system by using it to monitor the largest entry to your home. The Garage Door Sensor for AAA+ is designed to monitor the status of your garage door and advise you if the door is open. The built-in transmitter sends a wireless alert to your home security system upon a breach. The AAA+ Home Smart Center home security system is sold separately. # Transmitter # Lithium 3-volt battery # Mounting materials # Instructions