The product description isn't quite clear:
The box contains 10 bottles, and you've to apply one per day. The treatment course is supposed to be 90 days, so you will need at least 9 boxes if you wish to complete the treatment course.
I've so far tried one box, I find it makes my hair look and feel like it has too much product in it. I tried using just half a bottle on a couple of days, but it was still too heavy. I won't be completing the treatment course, because I don't like the look of my hair, and haven't seen enough improvement to justify a further 8 boxes.