The Litter Kwitter system was designed by animal behaviorists and veterinary experts to gradually change your cats behaviour using a series of plastic rings that fit over your toilet. You start by filling the red overlay (which has no hole) with litter and place it on the ground next to the toilet. After a week or so, you place it on the toilet. Your cat will instinctively jump up to find its litter and do its business. Once they are comfortable with this routine, you introduce the amber overlay which has a hole in the middle. After a while you replace it with the green ring (which has a bigger hole) and by now they are almost using the entire toilet. When you finally remove the green overlay, your cat will have become so accustomed to the routine that they will continue using the toilet without any overlay and you will finally be litter free.