Almost no new cars come without a remote locking system that comes as a key fob, or remote transmitter, that you can attach to your key ring. As technology improves, Key Fob comes with many new features. The key fob has buttons that allow you to lock or unlock all of your doors, open the trunk or hatch door, or activate a panic alarm which sounds the vehicle horn on and off. The key fob is powered by a small battery that over time will weaken, which will shorten the operating distance that you have become accustomed to when using your remote. Changing the battery in your remote transmitter will restore it to its former usefulness.