Morris 21799 Type S With Screw and Bar Knockout Seal, 4"

Product Overview

The Morris 21799 is a 4" Type S knockout seal with a pre‑assembled set screw and backer bar. It is made from galvanized steel and is intended to close unused knockout openings in electrical boxes, panels, and enclosures.

The pre‑assembled screw and backer bar slide into an open knockout and are tightened to secure the seal without removing box devices or covers.

Key Features

• 4" trade size (Morris catalog no. 21799)
• Galvanized steel construction
• Pre‑assembled set screw and backer bar for insertion without removing devices or covers
• Used to close unused knockouts in boxes, panels, and enclosures

What this knockout seal does

The Morris 21799 closes unused 4" knockouts in boxes, panels, and enclosures to protect exposed wiring and provide a mechanical closure.

• Closes open knockout openings to cover exposed openings in enclosures
• Helps maintain enclosure integrity when used as a mechanical closure

Materials and construction

Constructed from galvanized steel. The product is cataloged as Morris 21799 and sized for 4" trade knockouts.

• Material: Galvanized steel
• Catalog number: 21799
• Trade size: 4"

Installation method

The 21799 includes a pre‑assembled set screw and backer bar that slides into an open knockout. After positioning, the set screw is tightened to draw the backer bar against the interior of the enclosure and secure the seal.

• Insert the pre‑assembled screw and backer bar through the knockout
• Tighten the set screw to clamp the backer bar and secure the plug

Typical applications

Intended for closing unused 4" knockouts in electrical junction boxes, control panels, and enclosures where a screw‑and‑bar style plug is appropriate.

• Used to close unused knockouts in boxes, panels, and enclosures
• Applicable where a mechanical plug is required

Before You Order

Confirm the model number and trade size match your enclosure knockout before ordering.

• Model: Morris 21799 (Type S, 4")
• Material: Galvanized steel

Ordering from Lumera Electric

Check the purchasing options shown on the Lumera Electric product page for Morris 21799 Type S With Screw and Bar Knockout Seal, 4". For project quantities or additional ordering requirements, use Request a Quote and provide the required quantity.