Omega Paw Roll Away Self-Cleaning Cat Litter Box. It has no mechanical parts to malfunction. How does it work? Simply roll the litter box onto it’s top, and roll back to the up-right position. Remove the tray and dispose of the waste! The unique patented grate inside the Roll ‘n Clean scoops out the clumped waste depositing it into the pull-out tray. For fast, easy cleaning, use the Roll ‘n Clean Litter box