My chin has had a playpen attached to her cage for the last 4 years and has never tried to jump out. Until recently. She got out during the night. So after 4 years, I now have to shut her in her cage at night. During the day she still has not made an attempt to jump out. I am home for the most part and she sleeps most of the day away. If she starts planning a daytime escape, though, I will have to get a cover for her pen, which is the safest option anyway. I think some people line their pens with tall sheets of cardboard.