Interchangeable core locks, like high-security locks, have their uses. But there are also many instances where they should not be used. They are great for large offices, schools, dormitories, and locations where there are several levels of masterkeying. Their key advantage is that they are interchangeable. They do offer some degree of key control. If you are not frequently changing locks, they are probably not appropriate. Where they are used, somebody should be responsible for the locks. Interchangeable cores can be identified by their figure-8 appearance, like the Arrow brand interchangeable core shown below:
All the advantages of the interchangeable core disappear if you do not have a key known as a control, or core key. The control key does not actually operate the lock, but is necessary to remove or service the cores. Without it, the lock may need to be destroyed to remove the core. We've received numerous calls from small businesses wanting locks serviced or rekeyed. They will have interchangeable core locks, but no control key. If you are in this situation, you might want to consider replacing the locks now, rather than waiting for an emergency situation to occur.