I took a ride to Petco to look at the rolling litterbox. They had one which was regular size. I sat on the floor and put it together to see exactly how much space the cats actually have to do their thing. The space is approximately 12"x14", which ain't a hell of alot of room when you're trying to squat and go (from a cat's perspective that is). I'm going to look around for the jumbo size and do the same thing . If it has more room, I'll try it and let you know.