A word of warning if you upgrade from the Mini Duna to the Duna Fun Large, please note that the hole on the Large for the water bottle is on the opposite side to the tube which comes out, and so depending on where you put it (and how much room you have!) you might have to use a water bowl!! That's what I found!
I had to put the side with the tube on the outside which left the water bottle hole against the wall, so I couldn't use it... Now using a Ferplast Mary though so no problems!