Dr. Elsey's Precious Cat Ultra Clumping Cat Litter is a unique formulation that combines the heavy non tracking granules of the Classic with a medium grain clay. The result is an excellent clumping litter that prevents moisture from reaching the bottom of the tray, while providing a clump that will not break down. http://thepets4u.com/2018/04/25/dr-elseys-cat-ultra-premium-clumping-cat-litter/