I've been using one in chinnies' old cage and it worked fine with no problem, I love to watch them batting/turning the ball trying to get hay out. I'm still using the same one for the girls now, I tried the clay pot for them first, but little Totoro will pull all the hay out and sleep in there... this hay ball I can hang it up higher, so there's no way they can perch on it and soil the hay. Now Totoro will just popcorn over, grab a hay and hop away, up to no good somewhere else..LOL~