Hole Filler Plates

A hole filler plate is a metal cover plate used to conceal an existing bore in a door after hardware has been removed, relocated, or changed. It's one of the most overlooked items in commercial and residential hardware, but it solves a problem that comes up on nearly every retrofit job, tenant improvement, and hardware upgrade project. When a cylindrical lock, deadbolt, or mortise lockset is removed from a door and a new lockset doesn't cover the old bore, a hole filler plate is what closes the opening cleanly, secures the door structurally, and restores the appearance of the door face.

This category covers the full range of door hole filler plates and cylinder hole cover plates available at American Locksets, organized by the bore diameter they're designed to cover. Every plate on this page ships with the hardware needed for installation.

What Are Door Hole Filler Plates Used For?

Covering Old Bore Holes After Hardware Replacement

The most common scenario is a commercial or residential door where the previous lock occupied a 2-1/8" bore (the standard cylindrical lock bore) and the new hardware uses a different mounting position or footprint. On retrofit projects, tenant improvements, and residential upgrades, removing a deadbolt or knob lock leaves a 2-1/8" hole in the door face with nothing to cover it. A door hole filler plate closes that bore cleanly without requiring door replacement or patching.

The same situation applies when converting a mortise lock door to a cylindrical lockset. Mortise locks use a rectangular pocket cut into the door edge, and the cover plate or escutcheon on the face side doesn't always align with the new cylindrical bore. A door filler plate fills the gap where the old trim sat.

Adapter Rings for Thin Door Applications

Some hole filler plates in this category serve a different function: allowing a lever set designed for a standard 1-3/4" door to be installed on a 1-3/8" thin door. The Don-Jo AR9K adapter ring is a 3-1/2" diameter stainless steel ring designed to fill the gap between the rose of a cylindrical lever and the surface of a thinner door. Without the adapter ring, the rose doesn't seat flat against the door, which leaves a visible gap and creates a structurally weak mount.

Don-Jo Hole Filler Plate Models: Which One to Specify

Don-Jo BF-161 – The Standard Door Knob Filler Plate

The Don-Jo BF-161 is the most widely used door knob filler plate in commercial hardware. It has a 2-5/8" outside diameter and covers bores up to 2-1/8". The standard ANSI 161 cylindrical door prep is 2-1/8" in diameter, which makes the BF-161 the correct specification for covering virtually every standard cylindrical lock bore on the market. It's available primed for painting and in multiple finished options to match existing door hardware.

The BF-161 is specified on tenant improvement work, residential rental property upgrades, and any commercial retrofit where the old cylindrical bore is exposed and doesn't fall under the footprint of the new hardware. Two fasteners mount the plate from the outside, with the mating plate secured on the inside.

Don-Jo BF-135 – Large Bore Cover

The Don-Jo BF-135 is for larger hole applications, covering bores up to 3-3/4". This is the correct plate when the door has been modified, damaged, or when an older mortise escutcheon or auxiliary lock left a larger opening than the standard 2-1/8" bore. It's also used on doors that have been repaired and have oversized voids in the door face from failed patching attempts.

Don-Jo BF-178 – Small Cylinder Hole Cover Plate

The BF-178 is a 1-7/8" diameter plate that covers holes up to 1-1/2". This is the correct cylinder hole cover plate for smaller bores left by auxiliary locks, dead latches, security pins, or older hardware that used a smaller opening. It's individually packaged with a screw and is the smallest filler plate Don-Jo manufactures.

Don-Jo FPK-161 Filler Plate Kit

The FPK-161 kit bundles the components needed for a complete filler application on a standard ANSI 161 bore door. Specify this when a single plate isn't sufficient and a more complete coverage solution is needed for the specific installation.

Cylinder Plate and Cylinder Hole Cover Plate Applications

A cylinder hole cover plate is specifically designed to conceal the mortise cylinder opening on the face of a door after a cylinder has been removed and the remaining trim doesn't cover the cylinder bore. The Don-Jo 2-5/8" cylinder plate uses indents at the 3 and 9 o'clock positions to prevent the collar from shifting on wood or metal doors during and after installation. This detail matters on commercial metal doors where vibration and door traffic can work a flat plate loose over time.

Why These Plates Matter for Commercial Projects

On commercial punch-list work, a visible bore on a door face fails inspection. Building owners and property managers don't accept exposed holes on finished doors, and specifiers require that all hardware transitions be covered with appropriate filler plates or adapter hardware. Having the right plate in the right finish on hand before the inspection saves a revisit that always costs more than the plate itself.

Filler plates are also a security issue. An uncovered 2-1/8" bore is a structural weak point. A door with a hole in the face has compromised resistance to forced entry at that location. The plate restores the structural layer on both faces of the door and closes the opening against weather infiltration on exterior doors.

Browse the full hole filler plates inventory at American Locksets. For wrap-around plates that provide structural reinforcement along with bore coverage, see our builders hardware category. For new locksets to replace the hardware being removed, browse the complete commercial locks catalog.

Why American Locksets for Door Filler Plates

Ordering filler plates without knowing the bore diameter or door thickness gets the wrong part every time. At American Locksets, we carry the Don-Jo filler plate line in all sizes and finishes, stocked for same-day shipping. 

Frequently Asked Questions About Hole Filler Plates

Q: What is a hole filler plate?

A metal cover plate that conceals an exposed bore in a door after hardware removal. Restores door appearance and security where old knob, deadbolt, or cylinder hardware was removed.

Q: What size hole does the Don-Jo BF-161 cover?

The BF-161 has a 2-5/8" diameter and covers holes:

• Up to 2-1/8" (standard cylindrical bore)

• Available primed for painting or in finished options

Q: What is the difference between a hole filler plate and a cylinder hole cover plate?

A hole filler plate covers a cylindrical bore (2-1/8") on the door face. A cylinder hole cover plate specifically conceals the cylinder opening on a mortise-prepped door where only the cylinder has been removed.

Q: What door thickness do hole filler plates fit?

Most Don-Jo filler plates fit doors up to 1-3/4" thick. Adaptor rings like the AR9K cover thin 1-3/8" doors and allow levers to mount flat.

Q: When do I need an adaptor ring instead of a filler plate?

When installing a cylindrical lever set on a 1-3/8" thin door. The adaptor ring fills the gap between the rose and door face. A filler plate covers an unused bore, not a thin door gap.

Q: Can hole filler plates be painted?

Yes. The primed versions (PC finish) of Don-Jo filler plates accept paint and can be matched to any door color.