I have been a Littermaid automated catbox user for years.  This is the 5th one I have purchased and I would not ever be without it.  Littermaid had some problems in the begining and have done great improvements to their designs and operations.  This particular model is their absolute BEST.  It has a quieter motor, a larger, longer box (which is great for larger cats) and works great.  I have been through 4 different models, and when the last one finally wore out (it got ALOT of use with my 3 cats) I went back to this model, even though Littermaid has a newer model out.  Trust me...this Littermaid is the best, you will absolutely LOVE it.