1.[COMPATIBLE MODELS]—These premium FLT4100 HEPA replacement filter is specfically compatible with AC4100, AC4100CA, AC4150BL, AC4150PCA, AC4150P Technologies Models, compared to Part No. FLT4100 Filter E. NOTE: This is not OEM product. Any use of the brand name or model designation for this product is made solely for purposes of demonstrating compatibility. 2.[H13 TRUE HEPA]—These FLT4100 filters are made of H13 medical grade true HEPA filter, which can clean up 99.97 percent of particles as tiny as 0.3 microns from the air, such as fine dust, pollen, pet dander, lint, hair, fabric fibers, etc. 3.[ACTIVATED CARBON FILTER]- Our AC4100 activated carbon filters helps attaching common odors from pets, smoking, and cooking, wildfire, etc, providing a fresh and clean environment for your family and helping extend the HEPA filter's life. 4.[COST EFFECTIVE]—Package includes 2 x True HEPA Filter and 4 x Pre-Cut Activated Carbon Filter. It's recommend to replace the FLT4100 Hepa filter every 3-6 months and pre-filter every 2-3 months for optimal performance (depending upon your usage and environment). Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.