my cats are smart ... 
well, just place the Robot next to the old litter box, put some "used" litter inside. 2 days later remove the old litter box. The cats will learn.
my wife has nothing but praises because she hated the smell from the old cat litter box big time.
Now ... NO smell, seriously. The "stuff" is confined in a tray which is not open to open space like any litter box.
it's big though ... |