I've had my catgenie for almost one year now, and I'm super happy I bought it. Considering this thing scoops poop for you it's bound to miss some small pieces that will smell. That aside these granules least for a very long time. The box I bought one month after I purchased my catgenie is on track to last a year. I put a large beach type towel under the unit and it catches a lot of the granules my cat tracks out of the bowl.This makes it very easy to gather up all those tiny pellets and dump them back in the bowl to be used and washed again. I didn't expect the 3.5 pound box to last this long so I would very much recommend you get the catgenie for your furry little friends.