I use this inside and I only have one medium-sized domestic rabbit. It gives her plenty of room and allows me to clean it very easily - she was a bit shy going up the ramp at first, but - now she is a champ and really enjoys having the upstairs/downstairs options.  The casters are great - I just roll it out of the way when I have to clean underneath - and it is easy to move to another location if I need to.