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1-in Zinc-plated steel Knockout Seal Conduit Fittings

Ratings & Reviews for Sigma ProConnex 1-in Zinc-plated steel Knockout Seal Conduit Fittings

4.6
166
Review
 4.6 out of 5
166 Reviews


91% Recommend this product

Ratings may include incentivized customer reviews.

What Customers Are Saying

Customers overwhelmingly praise these plugs for reliable performance and snug fit in knockout openings. Most report they seal gaps effectively, preventing pests and dust while improving panel appearance. The rigid zinc-plated steel construction is frequently commended as durable and superior to cheaper alternatives. Installation is tool-free and quick, with plugs snapping securely into place. Many appreciate the flexibility to remove and replace them for future modifications. A few note sizing discrepancies or require significant leverage to install, but overall customers consider them an essential, code-compliant solution for electrical installations.

Customer review summary generated by AI, including incentivized reviews.
166 Customer Reviews

Easy to install

Would Recommend

Firmly fit

May 13, 2026
From 1_SLASH_2-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Works as needed

Would Recommend

Fitted and easy to install

May 13, 2026
From 3_SLASH_4-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Easy!

Would Recommend

The plug is easy to snap into place — like the knockout was never removed.

May 7, 2026
From 3_SLASH_4-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Excellent!

Would Recommend

Perfect for closing an unused knockout!

May 3, 2026
From 3_SLASH_4-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Does what it’s supposed to do

Would Recommend

Fit perfectly.

April 19, 2026
Verified Purchaser
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Unable to judge

Would Recommend

Unfortunately, it did not fit the hole in my junction box. The hole must be between sizes.

April 17, 2026
From 3_SLASH_4-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Perfect fit at a great price

Would Recommend

Great quality

April 16, 2026
From 1-1_SLASH_4-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Snaps into place

Would Recommend

Easy way to plug open holes in the junction box when wires are removed.

April 16, 2026
From 1_SLASH_2-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Dose not fit the boxes I bought

Would Not Recommend

Did not work like I thought

April 16, 2026
From 1_SLASH_2-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Response from Sigma Team

Thank you for your feedback of this Knockout Seal. We’re sorry to hear the knockout seal didn’t fit the boxes you purchased or work as expected. Knoc...

Sigma TeamApril 17, 2026

SigmaElectricManufacturing

Doesn’t get any easier than this

Would Recommend

Easy to install no tools required

April 16, 2026
From 1-1_SLASH_4-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Works as it should

Would Recommend

I was able to fill an old void without having to replace the whole electrical box

April 16, 2026
Verified Purchaser
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Inexpensive fix.

Would Recommend

Plugs holes like it should.

April 10, 2026
From 1_SLASH_2-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Perfect for missing/open holes in breaker panel.

Would Recommend

Easy to find, install and did the job perfectly

April 10, 2026
From 1-1_SLASH_2-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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They work well with a little finesse.

Would Recommend

These are a little stiff to insert but doable with a little bending of the fingers. They are also a bit pricy.

April 2, 2026
From 1_SLASH_2-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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Good fit in metal junction box

Would Recommend

I needed this part to seal up a knockout hole. It fit perfectly for a clean installation.

March 31, 2026
From 3_SLASH_4-in Zinc-plated steel Knockout Seal Conduit Fittings Verified Purchaser
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