Tubular pin tumbler lock

The devices have been widely used on vending machines, elevators, public computers, and bicycle locks.

The key is a cylinder shape with notches cut around the outer or (rarely) inner edge.

Each of these notches depresses a single pin inside the lock to a specific height allowing the lock cylinder to turn freely.

[1] Such locks can be picked by a special tubular lock pick with a minimum of effort in very little time; it is also possible to defeat them by drilling with a hole-saw drill bit.

[2] To prevent drilling, many tubular locks have a middle pin made from hardened steel or contain a ball bearing in the middle pin.