As a security system, rim locks provide the most basic of security. A common make of rim lock will have no more than 15 to 20 different keys. They are usually fitted for aesthetic and decorative reasons and in recent years the number of rim locks available on the market has diminished. In general, a rim lock is held on by four screws and its keep by two screws; hence anyone with a simple screwdriver can remove the lock internally and open the door.