I live at the beach and most of the year we cannot have the doors open due to hot and humid air as well as salt air sprayed from the ocean which coats everything and ruins electronics. Our dog loves to go outside to run and play on our balconies and this door is perfect for allowing her to do that without bringing in the salt air.Set and installation was easy. I just pulled it out of the box and set it in place. To assure a snug fit you just loosen the thumb screws and let the adjustable section slide up the meet the top of the door frame and then tighten the screws back. On the side with the sliding glass door just add the weather strip from bottom to top and you get a really good seal to prevent A/C leaking out or hot air in. Taking the door out is just as simple as putting it in.As for my dog, it took all of 5 minutes to teach her how to use it. She is scared of almost anything that is new to her so I figured that this might be a challenge. It turns out that all it took was a few dog treats and some small pieces of raw meat to teach her how to push the flap open to go out and back in. Now she is a pro at it and sometimes at night from my bedroom I can hear her go outside for a little while just to check things out.I highly recommend this dog door to anyone looking to give their dog 24/7 access to the outside.