What is master ring cylinder locksmith term?

A "Master Ring Cylinder" is a lock cylinder which has two independent shear lines accessible by a single keyway which allow for larger and more complicated master keying systems to be created.

The change keys operate at the inner (plug) shear line and the master level keys operate at the outer (ring) shear line. This allows for flexibility in that unassociated change keys can be used which will operate under any master key or combination of master keys in the system.

This is quite different from normal split pin locks in that in a standard cylinder associated master keys share several bitting cuts in common with the associated change keys within that same master key group.

Benefits of using a "Master Ring Cylinder":

- Very large, complex and vastly asymmetrical master keying systems are possible

- Immune to reverse engineering/rights amplification type attacks by persons possessing change key level keys from the system

Drawbacks of using a "Master Ring Cylinder":

- Requires the use of specific hardware which supports the special size cylinders limiting the options of what type of locking devices can be used in a Master Ring locking system