Arm & Hammer's Ultra Last Clumping Cat Litter has a highly effective formula, which contains Arm & Hammer Baking Soda coated granules and special odor neutralizers that continuously eliminate even the worst litterbox odors, according to the manufacturer. In addition, rock solid clumps allow for easy removal of the source of odors, and the moisture-activated fresh scent deodorizes the litter every time the cat uses the litterbox, the company states. The litter is designed to work even when pet owners can't clean the litterbox every day, and it's available in 20-lb., 28-lb. and 40-lb. sizes.