Don’t locksmiths have a master key that opens all locks?
That’s a common misperception. Master keys can be used for various purposes, and are generally set up in such a way that they will open locks related to keys of a specific group. For example, if you wanted to give a house key to your cleaning lady, you could masterkey a lock in your home to permit her access to that one particular door, while your MASTER KEY continues to open every door in the house! Another advantage is that you only need to rekey one cylinder if your cleaning lady ever leaves your employ—not the entire house!
