Unscented and Hard Clumping Multi-Cat Litter Our #1 selling litter — Ultra has superior odor control and is perfect for multi-cat families and those cat owners with sifting or mechanical litter boxes. Ultra is a unique formulation that combines the heavy non-tracking granules with medium grain clay. The result is an excellent clumping litter that prevents moisture from reaching the bottom of the litter box, while providing a clump that will not break apart. Ultra is perfect for single or multi-cat families and it controls odor naturally without perfumes or deodorants.