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0.375-in x 20-ft Closed cell Backer Rod, Gray

Ratings & Reviews for M-D 0.375-in x 20-ft Closed cell Backer Rod, Gray

4.6
1231
Review
 4.6 out of 5
1231 Reviews


96% Recommend this product

Ratings may include incentivized customer reviews.

What Customers Are Saying

Customers overwhelmingly praise this backer rod for effectively filling gaps before caulking, with most reporting it saves sealant, creates professional-looking finishes, and improves insulation by blocking drafts. Reviewers consistently describe it as flexible, durable, and easy to cut, compress, and fit into tight spaces without special tools. Many highlight successful use around doors, windows, trim, flooring, and driveways. A few note the diameter may be slightly smaller than expected, though this rarely affects results. Overall, customers consider it an essential, reliable solution for quality caulking preparation.

Customer review summary generated by AI, including incentivized reviews.
1231 Customer Reviews

Gap filler

Would Recommend

Great at filling in uneven gaps. Allowed me to have a good base for caulking.i would use again.

September 30, 2026
From 0.625-in x 20-ft Closed cell Backer Rod, Gray Verified Purchaser
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Great uneven gap filler

Would Recommend

This helped to fill in uneven gaps and allow me to get a good caulk line. I have used these gap fillers a few times and find them very versatile.

September 30, 2026
From 0.5-in x 20-ft Closed cell Backer Rod, Gray Verified Purchaser
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Had some extra large openings, needed to fill voids, and covered with chalking grout. Looks GREAT!!!

September 28, 2026
Verified Purchaser
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Would Recommend

Great filler for deeper expansion joints

September 28, 2026
From 0.5-in x 20-ft Closed cell Backer Rod, Gray Verified Purchaser
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Would Recommend

The gray color shows through a light color caulk. Otherwise, it does fill the gap.

September 25, 2026
From 0.5-in x 20-ft Closed cell Backer Rod, Gray Verified Purchaser
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Would Recommend

I found that the gray color shows through the white caulk.

September 25, 2026
Verified Purchaser
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Gap filler

Would Recommend

This worked great for a gap between sink and marble vanity.

September 25, 2026
Verified Purchaser
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Backer Rod - Garage door insulation

Would Recommend

When insulating my garage doors with 1 1/2' thick insulation, I used this backer rod on the low side to keep the insulation in the correct space for a secure fit. It compressed nicely to force the custom cut panel in, then expanded to eliminate movement. It was flexible enough to slide under the center braces, and the finished look was consistent across all panels. It worked great for this insulation project.

September 23, 2026
From 0.625-in x 20-ft Closed cell Backer Rod, Gray Verified Purchaser
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Easy to use

Would Recommend

Does the job easy to cut. It would be nice if it came in white.

September 23, 2026
From 0.5-in x 20-ft Closed cell Backer Rod, Gray Verified Purchaser
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Would Recommend

Best backer rod I have ever purchased

September 20, 2026
Verified Purchaser
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Works well; saves sealant

Would Recommend

I had a problem with my zoysia grass and weeds growing up in the cracks that were deep. I used sealant with backer rod to seal them off. It fixed the problem. I also scattered sand on repair when sealant was wet, it looks like the concrete. Backer rod keeps the self leveling sealant from runnig out the bottom of crack and reduces the amont of sealant needed. It solved the problem.

September 20, 2026
From 0.5-in x 20-ft Closed cell Backer Rod, Gray Verified Purchaser
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Great for sealing cracks.

Would Recommend

I bought this to fill in some cracks on my concrete steps before applying a self leveling caulk. It did a great job of sealing the crack.

September 20, 2026
From 0.5-in x 20-ft Closed cell Backer Rod, Gray Verified Purchaser
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