I had used twist ties to assemble their carry crate so that I could get it apart for easy cleaning. When I took them outside for their evening run, I guess they've gained weight because the entire thing fell apart halfway across the front yard. I freaked but they didn't. They obediently came to my feet to be picked up and carried inside the fenced back yard. Whew! Scary thoughts of traffic and the neighbors totally unrestrained pit bull! I now have the crate properly bolted together.