A play pen is a thing to keep the kid in one particular part of the room so they don't crawl off and hurt themselves. A fence, which can be attached in the doorway, you know, and it's locked and the kid can't open it unless a baby gate. We have a baby gate at the top and at the bottom of our stairs. And luckily, my boys have shown no interest in climbing up on them,. But I did see a YouTube video of a walking child in a nappy. So he must have been about one or just over one. There was a doorway with two baby gates, one on top of the other. They were complete almost completely up to