Good sturdy box
This is a really big, sturdy litter box with a very handy sieving system. I bought it hoping it would work with wood pellet litter (not what it's advertised for!) and it does, but you do lose some pellets. The holes in the sieve are quite big so the smaller pellets can fall through. So I ended up using one of the solid trays, then every few days I pass it through the sieve. Then any stray pellets can be sifted out with a scoop. Still far easier and faster than using a non-sifting tray I think.