As cats get older, they will have trouble using a regular litter box. The KittyGoHere Senior Cat Litter Box can help. It is a large box with a low 3-inch entry to make it easier for your old cats to get in and out. It has an open top litter pan for holder cats who have trouble getting through a swinging door.
This cat litter box is available in multiple sizes. This particular version measures 24 x 20 x 5″. It is ideal for cats up to 20lbs.