How does a master key work?

Master Key Hierarchy - Security Edge

Customer Managed Encryption Keys

A Master Key System: How Does It Work? - Matrix Locksmith

How does a master key work?

Master Key System in Los Angeles, CA

Everything You Need to Know About Master Keying

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Master Key Systems — A+ Safe & Lock

Master Key Systems

How Master Key Systems Work, Locksmith, Security

Is it possible for multiple unrelated keys that can open the same locks to be in the world? Or are there so many combinations of key teeth that it's impossible? - Quora

How Does A Master Key Work? - Guardian Safe & Lock LLC