My cat loves her Scoop Free Premium Blue Crystals Litter trays. I Love the dust free Crystals and definitely love the ease of changing once a month. It comes with 1 or 3 trays. Your paying for a premium and my baby is worth it.  We've used the box that uses the tray about 5 months and it's so easy to trade out the used litter. I'm happy and definitely recommend You tryit for yourself!