M-D Building Products - Versatile Gray Foam Backer Rod - Essential Caulk Saver for Sealing Concrete Gaps, Expansion Joints, and Crack Filling, 3/8 by 20 Feet (71464)

Stuffs easily into door and window cracks to provide insulation in irregular sized gaps. And works well as intended caulk saver for large cracks.

worked perfectly

Worked perfectly for the gap between the stair siding and wall letting up cold air. No more draft! Sturdy material and comes in one long piece so you can cut to size. Decent price

Exactly what I expected and needed. Solid and held up well.

Made up 20F difference before and after. I inserted this into a narrow gap between baseboard and floor. Wish I could've got 0.5', but a couple of go for this worked perfectly as well.

Had a small gap in my front door threshold after one of our animals ripped up the material that was originally in the gap. After reading many reviews for this product, gave it a shot. It was just what I needed! Super easy to use: measure, cut, install. Fits perfectly in the gap. No need to worry about dirt, bugs, and other debris getting in the gap. Great value too, as the 20ft bag was only about $3.00, with plenty left over if I need to replace it again. Highly recommend.

So I've been looking around for a way to fix my concrete driveway. Unfortunately the concrete expansion joints have separated and have made a pretty big gap. After much research I found that I should use a backer rod to lay in the expansion joints and than use a self leveling chalk to seal it in. This will prevent any additional water from eroding the base material under the concrete. I needed a couple different sizes as the width of the expansion joints was different as you went up the length of the driveway. I found what I needed. The M-D Building Products Backer Rod. I bought both a 1/4 and 1/2 sizes. I like to tell people about my shopping experiences in this case I'll cut and paste this same review for both the 1/4 and 1/2 sizes I received (no big differences in these). Both the 1/4 and 1/2 inch arrived on time. They were packaged very well. Super light as you can imagine. The backer rod is like a foam material. It fit well into the expansion joints. A nice snug fit. This is exactly what I was looking for. Otherwise with as wide and deep as these expansion joints have gotten it would have taken a lot of self leveling chalk to fill them in. The material cut really easy. I use my utility knife but an ordinary pair of scissors would have worked just fine. I was happy with the quality. I felt confident when install it in the expansion joints that it would hold up just fine and do the job.

Works well. I bought it to fill in gaps in my driveway. For the smaller cracks I cut the width of it. It is durable and a good price.

Great for posting my Dobermans ears thanks x

Good price for the quality of the product. Did the job.

Sometimes caulking or spray foam is not appropriate for the job, and is an excellent permanent base fix prior to caulking. Creates no pressure on door and window frames

Did exactly what it was designed to do.

Use in conjunction with hollow plastic rods (from Amazon) and lead tape to make shaft heavier after club assembly.