I took my time in measuring all of our windows. Some were out of square for sure. Our set of 11 inserts arrived in a big, well packaged shipping crate that was pretty straightforward to unpack. Nothing was damaged at all. Since our windows are big, I was expecting more of a challenge to install the inserts. It was a piece of cake after you learned how to squeeze one in properly. Every single one of them fit perfectly. As a result of covering most of our windows, there is a noticeable reduction in cold drafts. They're crystal clear so your view is unobstructed. You can hardly tell theyre there. I'm pretty happy with ours. I know they'll pay off in no time.