The bottom try is smaller than the pen, therefore there is a gap all the way around the pen. I called customer service and the woman told me she was looking at the pictures and could see that there was a possibility of it having a gap from one of the pictures. She also said that it just wasn’t the “right fit” for me. Instead of sending a huge package back, which was the only option I was given, I had to come up with something to fill the gap so my dogs foot doesn’t get caught.