I've got 5 crazy ferrets ranging from 1lb - 3.8lb and they always seem to find a way out of everything and into things they're not supposed to be in!! With this playpen (and matching playpen floor mat) I've only had 1 that has managed to get over the top of it - he is my longest ferret though and I maintain he got a really lucky jump or stood on one of the other ferrets because he hasn't been able to do it since. The playpen stands about 3ft tall (I'm only 5ft and it comes up a little past my hip). It is plenty big enough for my 5 to run around and dook, but I'll eventually get the 3 pannel extension to give them just a bit more space. When I'm done with the pen and they are ready to go back to bed, it folds up (almost completely) flat and is small enough for me to slide between the wall and my entertainment center so it is always handy next to their cage in the living room. also, the mat folds up and I just leave it on top of their FN cage. I think the best part about this playpen is it is made well and sturdy so they aren't able to knock it over. It clasps together along one side with 3 hooks (top, middle, bottom). The bottom hook was a bit hard for me to get into the hole at first, but it just makes me feel more confident that they aren't going to be able to hit it and knock it out of place.The only downfall for me was the price since it doesn't actually include the playpen floor mat. But, considering that my ferrets are like Houdini and can get out of *almost* anything, it was worth it in the long run and has proven to be a great help with cleaning out the cage and even when I recently moved, I was able to let them have some "free time" while we were moving boxes!! Not to mention it makes bath time so much easier so my couch doesn't get soaked with little wet body prints!! All things considered, I would buy this again in a heartbeat and am happy that I finally decided to shell out the money for it!