Filter-Monster branded replacement H13 True HEPA replacement filter compatible with Levoit Core 300, Core 300S, and Core P350 Air Purifiers. This filter is engineered to be compatible replacement air filter for Levoit Core 300-RF Filter. The H13 True HEPA filter captures up to 99.97 percent of particles as small as 0.3 microns including smoke, dust, pollen, pet hair and dander, mold spores, and dust mites. This helps to ensure improved indoor air quality. To ensure effective filtration, it is recommended to replace the HEPA filter every six to eight (6-8) months or more often depending on air quality and environmental factors. Included in the package are two (2) replacement filters.