They are to block off the males breeding run on the back of cages where ever you like. I recently used ours the other day. We had a female get her collar off and was in the run. She was sitting in the run next to her run hole. So I put the fork in beside her to keep her from running down the run and into another females cage while I blew on her to get her to go into her own cage. So yes they are handy when you need one.