In my opinion this product was a HUGE waste of money.

The rake that is supposed to comb the box and get any clumps only worked about half of the time.  The clumps would either stick to the rake or the rake would go right over the top of them. 
Sometimes the rake would even get stuck and keep going and going back and forth till the box had to be  reset. 

IT was such a pain to deal with that we just ended up unplugging the thing, and just use the scoop like we did before we had this box. 
It just didn't seem worth it to spend money on those plastic tubs when half the time the clumps weren't...