This is such a great buy for rodents bigger than a fancy mouse or dwarf hamster. This is only because they try to climb over it as well as through it. Getting up onto it was a struggle but it would have been better if they couldn't because they can't get down again safely. Unless your hand is there to help of course, but with more than one to keep an eye on in the play pen, not possible for me. My son now uses it like a posable robot arm. He seems to love the sound of it clicking open and closed between lengths. (I however am being driven made by it! lol) All in all though it is worth the money and plently of fun for Rats I'm sure.