Would not recommend to anyone with a dog larger than a JRT
The useful area is small - for a puppy or a toy breed. What's worse is that the door is very, very flimsy, and it is a sliding design, which means you only have HALF the opening for the dog's access. It makes the entry and the exit very tight and uncomfortable, and the security of the door very questionable.
We needed something urgently, otherwise I wouldn't have kept it.