Automatic Litterbox Central

It's more than a few pieces of plastic, glue and sealant.

These are built from rigid PVC (not the cheaper expanded PVC, as that will start falling apart in a few months) and encorporate my own lid design that actually works better than the original disposable units. I also researched and tested 5 different sealants until I found find the one that works the best with rigid PVC -- and won't come apart with long-term use. It's not just regular old silicone. I don't want my cat (or your cat) eating silicone.

They also come with a written guarantee personally signed by me in each box that says these are guaranteed never to leak, or I will replace it for free.

No disprespect to the posters, but we seem to have gotten off topic. I thought this thread was about different sources for refill cartridges.

So, my cheapest place to get refill cartridges is Meijer stores, at $15.00 a pop.