Review on Purrfect Portal XL Pet Cat Door: Easy Installation in Minutes for Large Cats (Up to 30 lbs) on Interior Doors - Secure Entryway with Molded Plastic Pass - Includes Instructions & Hardware, White by Shannon Judd

Easy to install if you have the recommended tools. Fits like it was made for a door, seems pretty solid (will update if anything changes). Our DOOOOM 21 lb cat easily fits the giant size; All cats dig the door, not the carpet (digging means 'like' for example, they like the door and the fact that they can get in and out of the room; they used to literally dig in the carpet, to get to our room ). Privacy can be an issue (at least for the large size) if you have very curious toddlers and use the entrance as a bedroom door, but nothing you can't handle. We like it, the cats like it, everything is fine in the world.