I get the OdorEze at PetClub, but you can probably find it at any large pet store. I used to use the Arm and Hammer one, but it didn't quite tackle it. When I got my second cat, and found out how picky she was, that was when I had to find something more potent. I now stock up on the boxes, and have a supply for both the upstairs and downstairs litter boxes. What I like about it is that you only have to sprinkle one package on top of the litter, and the cats mix it in naturally by digging.