Airmont Products (4 Pack) 4-Inch Square Metal Box with Side Mounting Bracket, Welded, 1-1/2'' Deep, with 2 AC/MC/Flexible Cable Clamps, Three 1/2'' knockouts, 1 TKO, Combination Screw Heads, New Work

Why I reached for this box

I installed the Airmont 4-inch square box during a garage lighting upgrade and a small shop build-out where I was running mostly MC (metal-clad) cable and wanted rigid, new-work boxes I could fasten directly to studs. I prefer welded steel for these environments—boxes get bumped during rough-in and trimmed later, and cheaper formed boxes can warp just enough to make device and cover alignment a hassle. This Airmont box’s welded construction and side mounting bracket promised a sturdier install and quicker layout.

Build quality and materials

The box is 4 inches square, 1-1/2 inches deep, with a 21 cu in volume. It’s made from 1/16-inch pre-galvanized steel and arrives with 8-32 cover screws and combination-head fasteners. The steel thickness is appropriate; it resists flexing and holds its shape when you’re wrestling conductors. Welds on my units were clean, and the stamping was consistent, so mud rings and device covers sat flush and square after trim.

Edges are reasonably deburred for a commercial-style box, though I still recommend gloves—like any steel box, there are corners that can catch skin or cable jackets if you rush. The pre-galv finish handles a typical garage or basement environment without any fuss. This is intended for dry or damp locations when used properly; it’s not a weatherproof box.

Mounting and layout

The side mounting bracket is designed for new-work framing. I attached it to studs with wood screws through the provided holes, and alignment was straightforward. The bracket allows a little play for fine-tuning depth to meet finish surfaces, but as with any 4-inch square, you’ll usually add a mud ring (plaster ring) later to match wall thickness and device requirements. For surface-mounted applications (shop or utility spaces), the bracket is simply a non-issue; you can face-mount the box directly to framing or blocking and finish with a raised industrial cover.

Combination screw heads on the bracket and clamps accept common drivers, which speeds up installation when you’re swapping between Phillips and square/flat; small detail, noticeable time saver.

Knockouts and clamps

You get three 1/2-inch knockouts and one TKO (a concentric knockout that can accept 1/2-inch or 3/4-inch fittings). The layout supports straightforward feeds, but it’s not a high-density knockout pattern. That’s fine for typical single-circuit or simple junction scenarios; it becomes a limitation if you’re branching multiple directions or mixing several cable types.

Airmont includes two preassembled clamps intended for AC/MC/flexible metal cable. For me, that’s the headline. The clamps bite cleanly, hold MC without slippage, and eliminate one more separate connector to inventory. If your job is mostly MC, this is efficient. If you’re running NM (Romex), you’ll likely rely on standard NM connectors through the knockouts; the built-in clamps aren’t meant for NM, so plan accordingly.

One practical note: because there are only a few knockouts, pay attention to entry orientation. On one of my pulls, I needed NM and MC to enter parallel and found myself rotating routes to accommodate the limited KO pattern. It worked, but it wasn’t elegant. A couple extra side knockouts would make this box more versatile.

Box fill and depth realities

At 1-1/2 inches deep and 21 cu in, this is a shallow 4-inch square. That’s an asset when wall depth or equipment clearance is tight, but it does constrain conductor fill and device space. For 12 AWG, 2.25 cu in per conductor is the NEC allowance; it’s easy to fill this box quickly once you count all the conductors, device yokes (which count as two of the largest conductors), internal clamps (which count as one), and equipment grounds. If you’re transitioning multiple circuits, adding a switch loop, or splicing pigtails for devices, consider a deeper 4-inch square (2-1/8 inches) or plan to add a raised ring to gain working space and protect conductors from being pinched at the cover.

In my installs, the 1.5-inch depth was perfectly fine for pass-through splices and a single device using a mud ring, but I wouldn’t choose it for complex junctions with heavy wire counts.

Electrical performance and grounding

The box is rated for use without a bonding jumper in circuits up to 600V. In practice, that means the metal enclosure can serve as the bonding path when used with appropriate metallic raceway or listed fittings. I still run a dedicated equipment grounding conductor and bond it to the box so device yokes and covers are unquestionably at ground potential—especially important when you mix cable types.

The integral clamps make a solid mechanical and electrical connection to the enclosure for MC. Thread engagement on the included screws was positive, with no cross-threading or soft metal feel. Cover screws are standard 8-32, and device rings and raised covers from the usual brands fit without fuss.

Before you order a big batch, check for required listing marks in your jurisdiction. The box I used did not clearly show a standard “Listed” mark I’m accustomed to seeing on electrical boxes. Your Authority Having Jurisdiction may require specific listings/labels, so verify what you’re buying and what’s stamped on the steel.

Installation experience

• Framing: The side bracket makes measuring and repeatable placement easy. It’s a new-work box first and foremost.
• Cable entry: Built-in AC/MC clamps saved time. They held MC securely without over-crushing the armor. For NM, I used separate NM connectors in the KOs.
• Knockout removal: KOs snapped cleanly without deforming the box walls. The TKO offered flexibility for a 3/4-inch connector when I needed to pull a larger flex run.
• Trim: Mud rings seated flat. The welded body helped keep everything square so cover plates sat flush—no shimming required.

Durability

After rough-in, these boxes took the typical abuse—ladders leaning, materials bumping—without going out of square. Welds stayed intact, and screw threads didn’t strip under normal torque. The pre-galvanized finish resisted scuffs better than some painted alternatives. It’s a box that feels “jobsite-proof” in the ways that matter.

Where it shines, where it doesn’t

Strengths:
- Welded construction that holds shape under load and during trim.
- Side mounting bracket for fast, repeatable new-work placement.
- Integrated AC/MC/flex clamps that actually save time and parts.
- Clean threading, included cover screws, and combination-head hardware.

Tradeoffs:
- Shallow 1-1/2-inch depth and 21 cu in volume limit complex junctions.
- Sparse knockout count means careful planning for cable orientation.
- Integrated clamps don’t help with NM; you’ll still use separate NM connectors.
- Verify labeling/listing to satisfy local inspection requirements.

Who should choose this

• Pros and DIYers doing new-work framing who run MC or flex and want integrated clamps.
• Garage, basement, and shop applications where a rigid welded box and stud-mounted bracket simplify layout.
• Projects needing a shallow profile to clear obstructions without resorting to pancake boxes.

Who should look elsewhere:
- Anyone planning dense junctions or multiple device transitions—opt for a 2-1/8-inch deep 4-inch square.
- Retrofit jobs in finished walls; an old-work box or adjustable solution will serve you better.
- Installations requiring more knockout flexibility on multiple sides.

Recommendation

I recommend the Airmont 4-inch square box for new-work installations that use MC or flex and benefit from a sturdy, welded enclosure with integrated clamps. It installs quickly, stays square, and takes a beating without deforming. Be mindful of its shallow depth and limited knockout pattern—great for straightforward circuits, not ideal for complex junctions. Before buying in quantity, confirm that the markings meet your local listing/labeling requirements. If those caveats fit your project, this box is a dependable, efficient choice.