Which type of cylinder is most commonly used on inward-opening or front doors?

• A. Rim cylinders
• B. Mortise cylinders
• C. Pin-tumbler cylinders
• D. Wafer cylinders

Answer: (A)

Rim cylinders are the type used with rim locks, which are mounted on the inside surface of inward-swinging doors. This setup is quick and non-invasive to install, since the lock sits on the door face and doesn’t require carving a deep pocket in the edge. For front doors that swing toward you, that simple, surface-mounted arrangement is often preferred, making rim cylinders the common choice.

Mortise locks pair with mortise cylinders and require cutting a pocket into the door edge, which is more labor-intensive and typically reserved for higher-security or traditional hardware. Pin-tumbler and wafer cylinders refer to the internal mechanism across various lock types, but they aren’t tied to the specific mounting style that defines front, inward-swinging doors in the same way rim cylinders are.