Mortise cylinders are commonly used in motel doors and aluminum framed doors on commercial buildings.

• A. Mortise cylinder
• B. Knob cylinder
• C. Rim cylinder
• D. Interchangeable core

Answer: (A)

The main idea here is matching the door construction with the right type of cylinder. Mortise cylinders are designed to fit into a recessed pocket inside the door that also houses a mortise lock body. This setup is common in motel doors and in aluminum-framed commercial doors because it provides a compact, secure, heavy-duty hardware arrangement that these doors typically require.

Knob cylinders are paired with residential-style knob or lever locks, which isn’t what motel or many commercial aluminum-frame doors use. Rim cylinders sit on the surface with rim locks, which are generally less secure and less common for exterior commercial openings. An interchangeable core is a feature inside some cylinders for quick rekeying, not a distinct cylinder type used specifically for motel or aluminum-frame doors. So the mortise cylinder best fits the described doors.