I haven't used this as a pen, but as a barrier. It is long enough to separate rooms when spread out. You can adjust the length by folding the sections. Might not work if you have a rowdy dog, but my 3 are afraid to touch anything that could move (and I have 2 Rottweilers and a Pit Mix). If one of them is having stomach problems which produces a mess from either end of their body, I "fence" them off in the dinette where there is linoleum. Works great!
Rating: [5 of 5 Stars!]