Here is the dial from the infamous Chubb mark IV manifoil lock. It is the lock that is fitted to many a high security container used by Police, Government and Military agencies. These are 4 wheel combination locks that are fully protected against all forms of covert attack. I have had to work on a couple of these recently that have been difficult to open. The mechanism is complex and requires specialist tools to take apart. At the first sign of one of these locks failing call a safe engineer out to have a look as they are very difficult to open when working let alone faulty!