Fister uses an uncovered litterbox and he's happy with it. It is 46 cm/18 inches long. It's in our 10 m corridor - no problem! We put clumbing litter in which are more expensive, but Fister prefers that and it's so much easier to clean. We usually empty it twice a day. A good (and economic) way of doing it, is to tip the box; all the clean litter will go to one end and you can just scoop up the rest with a small showel!