Amazing, never seen that before.
I'll just let him run free in the house though. Getting him to exercise enough does mean having to play with him, like rolling a ball over the floor which he can then hunt down. He is a bit spoiled that way.
He still runs around the house and plays when excited but running on the wheel has become his baseline activity when he wants to do something but I'm working and the other cat is uninterested in playing with him.
I'd definitely recommend it to anyone who wants to keep their cat indoors and exercised.
It'd be good if they could do something to improve the aesthetics though, the exterior of the circle is just bare injected plastic. http://onefastcat.com/media/catalog/product/cache/1/image/9d...