Description The ScoopFree litter box takes care of the scooping with its automatic rake that sweeps waste into the trap. The ScoopFree litter tray does the rest. Filled with crystal litter that controls odor, the disposable tray lasts up to 30 days before it needs to be replaced. Throw the disposable litter trays away. No scooping needed! 1 tray lasts up to 30 days for one cat, 15 days for 2 cats, and 10 days for 3 cats Silica crystals absorb liquid and bacteria on contact for long-lasting odor control and moisture reduction. With 99% dust-free crystals, you and your pet can breathe easy. Cats prefer a smaller granular litter because it feels softer on their paws. Low-tracking silica is less prone than clay to stick to your cat's paws. Choose from Premium Blue Crystals that reduce odor 5x better than clumping litter or Dye-Free Crystals without perfumes or coloring