If you use clumping litter, you know it's a great product with a major drawback...if the urine reaches the edge of the box, it causes a gooey mess which defeats the purpose of the product. I designed an easy to build box that has an integral 'stand-off' that keeps kitty centered in the box. ( I made a diagram, scanned it, but at 145 kb, it exceeded the limit of 14kb).