I ordered 2 at first without the door.  Using them outside as puppy house training area.  Hooked them together so puppy could have more space to run and play.  She loves them and they are holding up very very well.  As puppy was getting bigger I realized that it might be a good idea to let her go in and out without me picking her up and putting her in.  She will only be 15-20 lbs, but still is heavier then the 3 lbs she was when we brought her home. So I ordered another one with the door, now she has a bigger area outside and enjoys going in and out herself.  I can also take one of them with us when we travel and not have a big impact on her area outside, plus it feels like home when we are on then road.
Very Happy Puppy and Customer