Monitor your garage door through your Skylink AAA+ system by adding the Skylink Wireless AAA+ Garage Door Sensor. The sensor helps keep your home safe and secure by detecting unexpected operation of your garage door. When the garage door opens the sensor activates and signals the Control Panel (sold separately) to alert you. Rolling Code Technology Every time you press your remote transmitter to turn the security system on or off a code is generated which is recognized by the receiver that in turn performs the desired function. With most security systems there is only one assigned code. Whenever the remote is pressed it generates the same code making it vulnerable to code grabbers who use electronic scanners to steal the code. With rolling code technology each time the remote is used it generates a different code which can only be recognized by a rolling code receiver. Even if an electronic scanner picks up the code the next code will not be the same and the receiver will not recognize the old code. As a result security systems with rolling code technology are increasingly safe and secure. Note: Requires the Skylink AAA+ Control Panel (sold separately).