Nispira 3-in-1 premium HEPA filter replacement compatible with core 400S air purifier Compared to original part Core 400-RF HEPA filter removes up to 99.97 percent of airborne particles as small as 0.3 microns. Activated Carbon layer removes unfavorable odors from pets, cooking, smoke and chemical etc. Preliminary nylon layer captures large particles such as dust, hair, pet fur, debris. It also helpful to extend the life span of the filter. 4 Filters included. Filter size dimension: 9.3 x 9.3 x 10 inches Suggest to replace the filter every 6 months to maintain the best indoor air quality. 100% customer satisfaction guaranteed. Quality meets or exceeds leading national brands