This automatic cat litter box was rated The Best by the Hammacher Schlemmer Institute because it cleaned more quickly and thoroughly than all other models. Unlike inferior units that offered no control for setting its self-cleaning function and allowed waste to linger for as long as 20 minutes, The Best model enabled one to set the self-cleaning cycle to activate at three, seven, or fifteen minutes after a cat leaves. The Best model removed debris without the clumps and clogs that plagued other units, and its design is free of the standard rake mechanism that can injure cats and is prone to jamming. Instead, The Best Automatic Cat Litter Box offers animals a private space that cleans after use by sifting waste into a bottom drawer as it rotates upside down. It works with any clumping litter and has a carbon filter that helps prevent odors. With a sleep mode, nightlight, and enlarged opening of 15 1/2" H x 10 1/4" W to accommodate cats of any size. Plugs into AC with adapter. Sensor works with cats over 5 lbs. 29 1/2" H x 24 1/4" W x 27" D. (24 lbs.)