I purchased this for 1852. It is a 24 day supply. If I compare Fresh Guard to Retainer Brite, then the latter is better. Directions for use - take a glass of water, place powder in it, stir it using a spoon and immediately place retainer in the water. Wait 5 minutes. (I usually wait 10-12 minutes) Then you need to rinse in clear water and once rinsing is done, you can wear the aligners. Does a good job of cleaning. I am using this with my invisalign(s) In terms of both value and performance, i prefer the retainer brite. However, this arrives faster. I am further reducing my rating - 1. you have to stir it for sure. 2. the water blue evaporates in less than 20 mins shows how impotent is 3. weird taste in mouth...uggh what a turn off 4. just not worth the money