This C500FL filter is Compatible for the Homedics AP-C500 and AP-C550 Smart Air Purifier, Replace Part # C500FL. The C500 uses a 3-stage filtration system consisting of a pre-filter with carbon and a HEPA filter, that filters out a wide range of airborne contaminants such as pet fur, dander, and more. The package includes 4 x C500FL replacement filters, they are well made and inexpensive, very good value for money. Easy to replace and disposable, no tools required. Replace True HEPA Filter Set every 6-12 months for optimal performance. We're always here to deliver exceptional customer support. If you experience any issues with your filters, simply contact us and we'll resolve your issue. 4 Pack C500FL True HEPA Replacement Filter Compatible with Homedics AP-C500 and AP-C550 Smart Air Purifier, 3-In-1 Filter, Efficiency Activated Carbon, AP-C500FL