GermGuardian Air Purifier GENUINE Carbon Filter 4-Pack for use with FLT5000 HEPA Filter C for AC5000 Series Germ Guardian Air Purifiers, FLT28CB4 These are GENUINE GermGuardian Filters. It is important to only use genuine Guardian Technologies replacement parts to maintain product performance. Only one single combination filter needs to be replaced every 6-8 months depending on the use of the product. Contains 4 GENUINE carbon filters replacements for use with GermGuardian FLT5000 True HEPA filter for AC5000 series Air Purifiers including AC5000, AC5300B, AC5350B, AC5350W, also PureGuardian AP2800CA, Black+Decker BXAP250, and Lowe's Idylis IAP-GG-125 Activated charcoal absorbs household odors from pets, cooking, smoking and more. The replacement Activated Charcoal layer captures large dust particles and pet hair, extending life of the HEPA filter. According to the American Academy of Pediatric Allergy and Immunology, doctors recommend HEPA air filtration to reduce exposure to indoor asthma triggers.