Nispira True HEPA Filter Replacement for GermGuardian FLT4100 Filter E Fits AC4100 Air Purifier Model 1 Filter NISPIRA True HEPA filter with carbon pre-filter replacement for GermGuardian AC4100 Series HEPA filter proves to remove household dust, bacteria and germs from air with 99.7% efficiency. Charcoal Pre-filter reduces common odors from pets, smoking and cooking. It replaces FLT4100 Filter E. Filter dimension 1.5 x 6.2 x 8.2 inches. Suggested to replace every 6-8 months 100% satisfaction guaranteed. Premium quality meet or exceed the leading national brands.