The bottom of the litter box is inclined as it is constructed, and instead of the slope being downwards, it is upwards, resulting in the litter box being 5+ centimeters lower than the tray in the center. It cannot be fixed by hand, as it will probably break. This forces you to add much more sand (5+ centimeters), resulting in the level being too low, barely enough for the cat to do its business without throwing everything out of the digging area. The door has a huge gap due to the slope it has, at least 7 centimeters, nothing like the photo. Expensive for what it offers. The system with the two trays and the litter box works very well and saves time. That's why it got the stars, because the basic principle works correctly. In this specific case, however, you definitely need a lot of sand, almost filling the tray.