Ive been after an unbreakable cat flap for ages. The normal plastic ones done even last a year, the plastic 'arms' tend to snap, especially with dogs heads poking out. I think this flap will fit the bill. It has been well thought through and has a lot of positive features, especially the fact you can buy replacement flaps. There are however three negatives, and i do hope the manufactures will take this into account for newer models. 1) When fitting the flap onto a plywood door panel it became apparent the depth between the outside and inside sections was too wide, even after removing half of the width of the lip (There s nothing in the instructions for this but we presumed the indentation around the metal was for this reason?) We had to build a wooden frame for the flap to sit on. If your door is over an inch thick, you will be ok. 2) I always purchase a small flap, to prevent dogs getting out. This flap although it is small in width, is not in height, unbelievably due to this my normal sized whippet can get through it! Ive had to concoct a way of having the lock door sit half way down at all times to prevent this happening. 3) The biggest problem is it wont stay shut. Probably also due to the height of the flap itself. When the cat comes in the flap does not swing back shut...it is not catching on anything, it is all perfectly level. The rubber flap seems to remain bent for a while, when it straightens the magnets are not powerfull enough for the length of the flap to pull it shut. It has only been fitted for 2 days and as of yet we have not had any of the normal strong winds we have here, but i have no doubt it will blow open creating a huge cold wind tunnel into the house. I REALLY really want this flap to work, the aluminium frame, the rubber flap and how is it attached to the frame should ensure there is finally a dog damage proof cat flap. But at the moment the cons seem to outweigh the pros.