WIth 7 cats we had been using 40 pounds of cat litter per week (yes, you read that right); even at Costco prices we spent more per year on litter than the GNP of some small countries! Our little guys and gals took to it instantly. We added a second Genie about 1 1/2 years ago in order to eliminate the lines in the mornings. Since we didn't really have anywhere inside to put two Cat Genies we purchased .... get ready for it....a rabbit hutch large enough for both Genies, placed the hutch against a demising garage wall, added a cat door into it and voila! We have the perfect solution! Everyone is happy. We have no odor, no mess and the cats have total privacy.