Don't waste your money
This is possibly the worst self-cleaning litter box I have ever seen. I decided to buy one about 4 years ago and 2 weeks after getting it, the rake started getting stuck and making this loud clicking noise. After a few weeks, I got fed up with it and decided to give it go, and bought a new one. It did the exact same thing. I now own a Litter Maid, and so far it has worked out.