I absolutely love this cat box. This litter-box made my life easier. There has been absolutely no smell at all! 
 To change it out just lift the plastic unit up, slide out the old box (the soiled litter is under a flap), and use the lid below it to place on top then discard. After a quick wipe down with a sponge, the new box will slide underneath and we'll be good for another month. My cat love a fresh litter box every time he enters.