I just use regular covered litter boxes. I got my first covered box because I had a cat that even though he used the box, he would not squat, so the urine stream was always on the wall. With the cover, it would hit the lid and drip into the box. And litter doesn't usually get dug out of the box, only tracked out on paws. And I use carpets andd other forms of litter catchers at the entrances.