Review on VEVA HEPA and Carbon Filter Replacement Kit - 2 Pack HEPA Air Filters & 6 Carbon Pre-Filters - Fits Air Purifier Series AC5000, AC5250PT, AC5300B, AC5350W, AC5350B, CDAP5500B & AP2800CA by Kathy Lee

These are great filters that offer a cheaper alternative to GermGuardian branded replacement filters. They fit perfectly on my AC5350B. I love how many carbon pre-filters are included in this pack. I change them as soon as the black turns gray from dust and other contaminants. The True HEPA filter lasts quite a long time. I leave my filter on 24/7 at medium speed (set to 3, max 5). It never turns off and the HEPA filter will last a few more months before it too starts turning gray and dirty. When it's gone white, I know it needs to be replaced. VEVA makes great filters and I highly recommend them!