Those are warded locks, master keys (nothing to do with the Master Lock company) are keys which can open a large group of locks in a specially prepared locking system.

Locksport enthusiast Bosnian Bill demonstrates how to open a new #3 Master Lock with nothing more than a small brass hammer. The process isn't bumping exactly, but it looks as if the locking dogs ...

Three hackers have developed and released a 3D printable master key used by Transportation Security Administration, which opens Safe Skies luggage locks. During a talk given on Saturday, the three ...

Master Lock has a process for people to retrieve old locks combinations. Here's how it works.