SmartCat Lightweight Clumping Litter is ½ the weight of traditional clay litters. This litter creates a rock hard clump, that you have to see to believe. Not only is the clumping unbeatable, this litter is also lightweight. The technology stops odors on contact, and is 99% dust free. SmartCat clumping litter is light in weight but strong in performance. 99% Dust Free. ½ The Weight Of traditional clay.