I love this thing! Perfect size for my small dog. I got the smaller size, for a medium dog it kinda depends, but keep in mind the height on this one is lower, it’s not very tall. It’s very cute to look at and easy to fold up. I use it as his crate at home and then bring it whenever we go to the office or other places. I love that at night I can fit his bed in it with a little room to spare but if I want him to have more space I can just take the bed out. The zipper roof is nice to have too, depending on how spunky my dog is being that day.