I waited awhile after starting to use the crystals to write my review to see how well they truly work. I am very pleased!! The cats do not track it out the litter box which alone makes it worth it. It also lasts a lot longer.  We use a self scooping litter box and I am able to go much longer between adding more to the box. The crystals control the odor much better also. I also think it has deterred our dogs from going in the litter box. This is definitely a huge improvement over traditional litter!!