Disposable trays prefilled with blue crystal litter, made for the PetSafe ScoopFree self-cleaning litter box. The crystals absorb urine and quickly dry out solid waste to stop odours. • Fully disposable tray, you never see or touch waste • 99% dust free litter • Plastic liner helps prevent leaks • Up to 30 days per tray for one cat Swap in a new tray and your box is good as new.