I recently purchased two "Rollin' The Hay" hay dispensing Balls from SUPER PET to find that they are highly dangerous to guinea pigs!
_Super Pet - Pets International, Ltd._
(http://www.superpetusa.com/index.html) Item #61917
I came home from work to discover that my cavy had managed to knock the dispenser off of the bars of the pen, open the door that is supposed to "lock shut", and was trapped in the ball. His front legs and head were trapped in the ball itself, and his hind legs were entangled in the metal hanger. I thought he was dead, but luckily he survived with few injuries.
I would NOT recommend these as pet safe in any situation.
[Direct link to product: http://www.superpetusa.com/catalog/viewone.asp?itemNumber=61917 -- Lynx ]
I know I would have bought it when we first got Angel if I would have seen it, just because it was all about 'cute stuff' back then. :s
- I GAVE, dammit!