I bought three inserts primarily for sound abatement, as our new neighbors installed a new AC compressor/air handler eight feet from our bedroom window. To be honest, I was skeptical at how much it would help; and in reality, it helped some, but not as much as I wished. We also installed blackout curtains and will try to get our neighbors to put up a sound-reducing blanket. As far as the inserts, they seem well made and fit well. The only quibble I have is that on two of the inserts, there is a bit too much insulation at the corners and they bunch up. I was able to fiddle around and fix one, but the other still leaves a small gap in one corner. Given the price, I would expect the fit to be perfect, and if I were buying them primarily for insulation, I'd be upset.