Unfortunately, they don't last very long. Fortunately, I got free replacement from them under warranty.
The "clumps" stick to(in) the grate - making a nasty mess to clean up (scrape off). Other than that I love everything else about the product
I recommend the Chill X Auto Egg
One of my cats is 17lb, she’s a fatty lol. She loves the Auto-Egg though
It works better than okay but it will get stuck some times and it is kinda louder than I thought it would be. The experience is pretty good overall