The Garage Door Receiver 318R is part of a wireless system that allows you to control your garage door opener with transmitters that are easier and more convenient to access. Whether you prefer to open your garage with a personal access code or would like the convenience of a transmitter that resides on your key ring, the Garage Door Receiver will allow for peace of mind and ease of use. The Garage Door Receiver is controlled by either a Keyless Entry Transmitter or a Keychain Transmitter, both sold separately. Either the Keyless Entry Transmitter, which mounts on your garage wall and requires a personal access code or the Keychain Transmitter, which allows easy garage access, each transmitter will send a wireless signal to the Garage Door Receiver, alerting it to open the garage door. Both of these transmitters are sold separately. The Garage Door Receiver is easy to install. Connect the stripped ends of the included wire to the two terminals on the back of your wall-mounted door control, and plug the connector end into the receiver. That's it. If you're using the Keychain Transmitter, its left button is preprogrammed to operate the receiver. There is no limit to the number of transmitters that can control the Garage Door Receiver, so every member of your family will be able to access your garage. Simply set the same operation code on all transmitters with the same code setting on the receiver.