PrettyLitter is a clump-free litter, made of super absorbent, lightweight silica gel. SIlica gel crystals are extemely absorbent, more so than other litter substrates, so you need less of it to do the same job. Traditional clumping litters turn urine into large (heavy) clumps to be scooped out. This litter that is clumped, scooped, and disposed needs to be replaced throughout the month. This means more litter, heavier bags, and more trips to the store. PrettyLitter is a non-clumping formula, so you only need to scoop and dispose of the feces. This allows the one bag to last an entire month! No replenishment throughout the month needed.