I don't know if any of you use the ScoopFree automatic litter box with cartridges, but just in case: The manager of my local PetSmart saw me buying a cartridge the other day and told me that he had just heard from his ScoopFree guy that they were having production issues and wouldn't have any more inventory until sometime in August. And, indeed, there were only a few cartridges left on the shelves. I have no independent confirmation of this, but I bought a six-pack from Amazon just in case. (They also have the three-pack and single cartridge.) Of course, all of those items are currently in stock, which makes me question the "shortage," but hey, better safe than sorry, right? It's not like they'll go bad.