This is LeBob having a "ball". I'm not sure if they are referring to another type of ball besides the hamster one, but mine sure does like traveling in it. His shell is finally heavy enough so he can walk around the room. He's a medium.
I've seen stuff on ebay in a grouping for sale. It's always been a hamster ball. In fact I saw one that had a race track you could put the ball on, so they could go around and around - it looked cool!