The PetSafe ScoopFree Crystal Litter Tray Refills are ideal for those who are looking for an quick and easy way to clean up after their pets. The tray refills are made of premium blue crystals that absorb urine and quickly dry solid waste, removing odors 5 times faster than clumping clay litter. Simply remove the disposable litter tray when it's time to clean up and throw it away.