We have just purchased this add-on for the Zhu zhu hamster playset, and its ok. The hamsters go in the wheel and use it ok, they even turn round if you try and put them in facing the wrong way (v clever). However they can never ever get out of the wheel and back into the tunnel without help. They end up sideways or upside down and then they turn off. Not a big problem but one that is fairly annoying, as is the fact that if you have more than one hamster, they dont notice when the wheel is being used(i.e with their nose), and once they pass the entry to the tunnel to the wheel, they all get stuck. I would have thought they would perhaps be able to reverse back down the tunnel like they do if you put them in the wheel the wrong way...but no. Good toy, but slightly expensive for what it is. Though would reccommend it, if you dont mind giving a little helping hand...