Orbit 4SB-MKO-EXT 4" Square Ex...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$3.90
Orbit 4SB-MKO-EXT 4" Square Extension Ring, Welded MKO, Galvanized Steel

Orbit 4SB-MKO-EXT 4" Square Extension Ring, Welded MKO, Galvanized Steel

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Model: 4SB-MKO-EXT

In Stock (leaves warehouse same day if ordered before 3pm ET)

$3.90
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Orbit 4SB-MKO-EXT 4" Square Extension Ring, Welded MKO, Galvanized Steel

The Orbit 4SB-MKO-EXT is a 1-1/2" deep, 4" square (4S) extension ring built from 16 gauge galvanized sheet steel with a welded construction and modular knockout (MKO) sides for versatile field wiring. Offering 21 cubic inches of usable box volume, this extension ring is designed to add depth and wiring capacity to existing 4" square electrical boxes, giving electricians the extra room needed for larger conductor counts, additional devices, or bulkier splices without replacing the entire box assembly. Made in the USA-standard 16 gauge steel gauge, the ring is engineered for durability in commercial and residential rough-in applications where corrosion resistance and long-term structural integrity are required.

Key Features

  • Trade Size: 4" square (4S) footprint with a 1-1/2" extension depth, matching standard 4S box dimensions for a clean, flush fit.
  • Durable Construction: Fabricated from 16 gauge galvanized sheet steel for corrosion resistance and long service life in rough-in electrical work.
  • Welded Assembly: Fully welded seams provide a rigid, one-piece extension ring that resists flexing and separation during installation.
  • MKO Knockouts: Modular knockout (MKO) sides allow installers to open only the conduit entry points needed, reducing unnecessary openings and keeping the enclosure protected.
  • Added Wiring Capacity: Delivers 21 cubic inches of additional box volume, helping installations meet fill requirements when adding devices or conductors to an existing 4" square box.
  • Finish: Galvanized finish for added protection against rust and moisture in a variety of installation environments.

Technical Specifications

  • Size: 4" x 4" x 1-1/2"
  • Volume: 21 cubic inches
  • Gauge: 16 gauge sheet steel
  • Material: Galvanized steel
  • Construction: Welded with MKO (modular knockout) sides

Typical Applications

  • Extending Existing 4" Square Electrical Boxes
  • Commercial and Residential Rough-In Wiring
  • Adding Box Fill Capacity for Additional Devices or Conductors
  • Conduit and Raceway System Terminations
  • New Construction and Remodel Electrical Installations

Why Orbit?

Orbit's 4SB-MKO-EXT extension ring is built from 16 gauge galvanized steel with fully welded seams, giving electrical contractors a rugged, code-friendly way to add depth and volume to standard 4" square boxes. The modular knockout design keeps installation flexible while maintaining the structural integrity electricians rely on for demanding commercial and residential projects.

Manufacturer Resources

Product Specs

list_batch:
ORB-20260924
Product Type:
Box Extension & Adapter Ring
Product Finish:
Galvanized
Configuration:
Welded, MKO Knockouts
Department:
Electrical
Product Subgroup:
Enclosure Accessories
Product Material:
Galvanized Steel
Product Size:
1-1/2"
Product Group:
Boxes & Enclosures

Orbit 4SB-MKO-EXT – Frequently Asked Questions

1) Will the Orbit 4SB-MKO-EXT extension ring fit a standard 4 inch square box?
Yes. The 4SB-MKO-EXT matches the standard 4S footprint at 4 x 4 inches, with a 1-1/2 inch extension depth, so it sets flush on an existing 4 inch square box. It is not sized for 4-11/16 inch square (52-style) boxes or for octagon boxes.
2) How much box fill does a 1-1/2 inch deep 4 inch square extension ring add?
21 cubic inches of usable volume. That gets added to whatever the existing 4 inch square box already provides, which is how electricians clear a fill calculation after adding devices or pulling extra conductors through an existing box instead of tearing the box out.
3) Can I use a galvanized steel extension ring outdoors or in a damp location?
The 16 gauge galvanized steel on the 4SB-MKO-EXT gives corrosion and moisture resistance for rough-in work, but it is not a weatherproof assembly on its own. For an exposed exterior one-gang application where you need a gasketed weatherproof build, the Pass and Seymour WPEX Series weatherproof extension ring is the type to look at instead.
4) My 4 inch square box is buried too deep behind new drywall or tile. Will this bring it to the surface?
That is the main use for it. The 4SB-MKO-EXT adds 1-1/2 inches of depth on top of an existing 4S box, which brings the device plane forward after added wall thickness, without replacing the box. If your added build-up is less than 1-1/2 inches you will want a shallower ring or a raised device cover instead, since the ring will stand proud of the finished surface.
5) Is the Pass & Seymour WPEX extension ring an alternative to the Orbit 4SB-MKO-EXT?
They serve different openings. The Orbit 4SB-MKO-EXT is a 4 inch square extension ring in galvanized steel, 1-1/2 inch deep with 21 cubic inches of added volume and welded MKO knockout sides, so it stacks on a standard 4S box. The Pass & Seymour WPEX series is a weatherproof one-gang extension ring in gray, built for a single-gang weatherproof body rather than a 4 inch square box. If the existing box is a 4S, the Orbit ring is the matching footprint; a one-gang weatherproof device box takes the WPEX.
6) What does MKO mean on an extension ring, and why would I want it?
MKO stands for modular knockout. The sides of the 4SB-MKO-EXT come with knockouts you punch out only where you actually need a conduit entry, so unused openings stay closed and the enclosure stays sealed up. If your conduit runs come in from a direction you have not finalized yet, the MKO sides let you decide in the field rather than on the order form.
7) Is a welded extension ring better than a drawn or crimped one for conduit work?
Welded means the seams are joined into a rigid one-piece ring, so it does not flex or pull apart while you are torquing conduit connectors or screwing devices down against it. That matters on conduit and raceway terminations where the ring takes mechanical load. The 4SB-MKO-EXT is the welded version.
8) Does an extension ring come with a cover or mounting screws?
The 4SB-MKO-EXT is the ring only. You supply the device cover or blank plate for the front, the connectors for whatever MKO openings you punch, and the screws that fasten the ring to the existing box. Plan those into the order so the opening gets closed out in one trip.
How fast can I get the Orbit 4SB-MKO-EXT delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Orbit 4SB-MKO-EXT come with a warranty?
Absolutely. The Orbit 4SB-MKO-EXT is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Orbit 4SB-MKO-EXT?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Orbit 4SB-MKO-EXT from ZenSupply?
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