content: This is one of the most wonderful items for ferrets and rats! It can be rearranged any way you want to, and you can get more sets to create an even more fun time for your small pets. Its sturdy, it has ventilation holes, and it comes apart completely for cleaning. I had a set for my pet rats, and they loved it. now i have a ferret, and she really likes running around in it and hiding her favorite toys in it.I highly recommend this product, and it can fit in some of the larger cages, too. You just cant go wrong with this, its fun for your pet and it fun for you to watch them play with it.