Ultra Micro Crystals cat litter is the ultimate non-clumping litter for odor control. Ultra Micro Crystals are made with the highest quality Silica Gel crystals available. Silica Gel is safe, non-toxic and allergen-free. Not only are Ultra Micro Crystals safe for cats and people, they are also lightweight with high absorbency properties, requiring less litter than clay and other types of litters. This means, using Ultra Micro Crystals, less litter per cat ends up in the landfill. Ultra Micro Crystal when used as directed will control litter box odors for up to 30 days, keeping the litter box fresher, longer. Ultra Micro Crystals are super soft on paws to give cats a pleasant litter experience.