Gardner Bender KO710 Knockout Seal

Yes. The KO710 metal knockout seal installs from either the inside or the outside of the box, so a panel already mounted against a wall is not a problem. One screw holds the seal in place, and the embossed face self-centers it in the unused knockout as you tighten.

It's 16-gauge cold-rolled galvanized steel, rust-proofed, and the screw and bar are zinc-plated. That plating on the fastener matters as much as the seal itself, since a bare screw is usually the first thing to corrode in a humid mechanical or laundry room.

It's a screw-retained seal, not a threaded plug you spin into the hole. A single screw and bar clamp the steel disc over the open knockout from one side. The 3/8 inch thread refers to the screw hardware supplied with it.

No extra hardware. The screw and bar come with the seal, both zinc-plated, and a screwdriver is all the tool you need. Nothing has to be reamed or tapped in the enclosure.

On a steel enclosure, a metal seal like the KO710 keeps the barrier the same material as the box, and the galvanized 16-gauge disc with its zinc-plated screw and bar gives you a mechanically fastened closure rather than a friction snap. Plastic snap-in plugs go in faster with no tools, but they rely on the hole edge to hold and are the easier of the two to knock out accidentally.

Each Gardner Bender seal is stamped with its size and catalog number right on the face, so a seal pulled loose from packaging is still identifiable on the job and the inspector can read it in place.

The KO710 ships as a package weighing 77.8 ounces and measuring 5.75 by 5.75 by 1.13 inches, which is a multi-piece carton rather than one loose seal, so it suits a contractor or MRO shop stocking a van or crib rather than someone patching a single hole.

Order it as Gardner Bender KO710. The UPC on the package is 032076007102.