Sifting Boxes: As the name implies, these litter boxes work by utilizing two pans as well as a sifter tray. The two pans are stacked on each other and the sifting tray is kept in the top pan. When you want to clean the box all you do is separate the litter boxes and lift out the sifting tray which will remove waste while leaving the clean litter allowing you to restack the pans with clean litter.