I've had my CatGenie for 2 1/2 years, and I will never have anything else! This maintenance cartridge is great for keeping the gunk from building up on my Genie. I also do a thorough-take it apart-and clean!! A few spots were dirty, but overall, the maintenance cartridge keeps it fairly clean. I was getting this through Petco so I could earn rewards, as I have other animals. But...they are always out of stock! With the rewards you get for shopping on this site, I actually saved a little!