Product review (3 stars): Set of three means 3 in total. Also they don't last long.
I bought these to replace my permanent filters that I left in my unit too long. These new ones last about 3 weeks before they get gross. The unit is a bad design because as other reviews said it seems half way in the water makes it get disgusting. I removed the plug at the top and flipped it over (after washing it out) after 3 weeks and that gained some extra time, but overall these don't last like they should.