ScoopFree is a revolutionary automatic litter box that uses disposable nomess litter cartridges, preloaded with Fresh Step brand crystals. You simply replace the cartridge about once a month for each cat. That's it90Day Guarantee: If you are not satisfied with your Scoop Free within 90 days of purchase just send it back to us for a product cost refund (shipping is nonrefundable) Includes One Cartridge Using FreshStep OdorAbsorbing Crystals Selfcleaning litter box measures 19 wide by 273/8 long by 7 high Litter tray measures 141/2 wide by 22 long by 21/2 high UL Rated Power Supply Fill And Leave For Up To 30 Days No Mess To Touch Changing Cartridges Is Fast And Easy Unbeatable Odor Control Recommended litter tray replacements: At least once every 2030 days for one cat, every 1015 days for 2 cats, every 710 days for 3 cats Cats love ScoopFree because it keeps their litter box clean and fresh. Cat owners love ScoopFree because there is nothing messy to see or touch. Fresh Step Crystal litter offers unbeatable odor control and the Scoop Free automatic litter box provides superior convenience.