Schlage Commercial A501-566 - Door Reinforcer, 1-3/4" Hollow Metal Doors

That is the exact opening it is built for. The A501-566 is a door reinforcer for 1-3/4 inch hollow metal doors, which is the standard commercial door thickness, so it suits typical steel corridor, stairwell, and entry doors. It is a single-thickness part, so if the door measures anything other than 1-3/4 inches, this is not the reinforcer for it.

The A501-566 is an A Series part. Schlage A Series is the company's cylindrical (bored) knob and lever line, so this reinforcer goes with an A Series lockset installed in a 1-3/4 inch hollow metal door. If the door carries a mortise lock or an interconnected set rather than a bored A Series lock, this is the wrong part.

Commercial. The A501-566 reinforcer is part of Schlage's commercial line, which is what you want behind an A Series lock on a hollow metal door in an apartment corridor, school, healthcare, or office opening carrying steady traffic. It is a replacement part, so it is the item to order when you are restoring a worn or damaged lock prep rather than buying a complete new lockset.

Match the finish to the lockset on the door. Many Schlage replacement parts are finish specific, so a reinforcer ordered in the wrong finish will not blend with the A Series trim already on the opening. Pull the finish off the lock you are servicing before you order, especially if you are standardizing a run of doors that all need to look alike.

It is a certified Schlage part, ordered by the manufacturer's own model number A501-566. That matters if you are keeping a building standardized on Schlage A Series hardware and need the repair part to carry the same identity as the lock it supports, rather than a generic reinforcer that may not line up with the A Series prep.