I installed a cat door through a wall to our deck, so needed four of these to connect, which adds up to nearly 7 inches. To connect two pieces, they need to overlap by about an inch, so I needed to order one more than I planned, and I had to saw off the extra material, which wasn't easy with the wrong kind of saw.After all that, the cats will only go out through it, then they get stuck outside . I'm not sure why, except that maybe it is difficult for them to make the slight jump up into what amounts to a little tunnel, which is uncomfortable for them to crawl through? I don't think it's a flaw of the product, but it is a bummer that I went through all the time and expense, and it isn't working for us.