The Hammacher Schlemmer Institute enlisted a cat behaviorist to test leading self-cleaning litter boxes, and this is the one overwhelmingly preferred by felines and owner alike. Its auto-sensing sifting comb quickly and thoroughly cleans the box every time, unlike lesser models that operate too slowly and frequently clog or leave debris behind. As a result, the expert observed it was the only litter box used consistently by all cats throughout the test. Waste is deposited into an airtight holding receptacle that eliminates lingering odors and removes easily for sanitary disposal. It is the only model that keeps the surrounding area mess-free, thanks to its large plastic tray and a carpeted ramp that collects litter from cats' paws, preventing it from being tracked throughout your home. Requires clumping-type litter. Includes 12 waste receptacles and four odor-absorbing carbon filters. Plugs into AC or uses eight D batteries (not included). 8 1/2" H x 16 3/4" W x 29" D. (9 lbs.)