Cylinder locks

Cylinder locks feature a key with a serrated edge that aligns spring-loaded pins within the lock cylinder to allow entry. This innovation significantly increased security for locks by making them difficult to pick and easy to mass-produce with unique key combinations.
 Linus Yale United States 1865 Cylinder locks

Cylinder locks feature a key with a serrated edge that aligns spring-loaded pins within the lock cylinder to allow entry. This innovation significantly increased security for locks by making them difficult to pick and easy to mass-produce with unique key combinations.