This lock features the patented Octagon mechanism. Only patented locks and keys can prevent unauthorized duplicate keys being cut or blanks being made. The patents enable users to regulate the issue of keys very strictly, ensuring that registered keys are only ever issued to the relevant customer. This allows users to operate two or more types of locks using the same key. Where the lock types can be master keyed, there is also the option to have two or more types of locks operated by different keys, and a master key that will open any lock within the set.