Pre-filled with crystal litter, the ScoopFree Original Scent Disposable Crystal Litter Tray works with ScoopFree Self-Cleaning Litter Boxes. Just load the tray in the litter box for weeks with no scooping, cleaning, or refilling! The crystal litter absorbs urine and dries solid waste quickly to remove odors. With the completely disposable tray and waste trap, you never see or touch smelly waste! Every few weeks simply replace the litter tray, and your ScoopFree Self-Cleaning Litter Box is just like new.