Model Compatibility: The Filter-Monster 4-in-1 True Replacement Air Filter is designed to be compatible with Levoit Core 300, Core 300S, and Core P350 Air Purifiers. Compatible replacement for part number Core 300-RF-WS. Integrated Carbon: The Filter-Monster 4-in-1 Replacement Air Filter has integrated carbon that reduces household odors and VOCs (volatile organic compounds) from cooking, cleaning chemicals, and smoke. Replacement Time: Depending on air quality environment and usage, it is recommend to replace the filter every six to eight (6-8) months to help ensure the Levoit air purifier is running efficiency. Dimensions: The Filter-Monster 4-in-1 Replacement Air Filter is compatible with Levoit Core 300, Core 300S, and Core P350 Air Purifiers, the approximate dimensions for the filter are 7.5” x 7.5” x 5.75”. Included in the package are two (2) replacement filter. Filter-Monster branded replacement 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-WS Smoke Remover Filter. The 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 improve indoor air quaility. To ensure effective filtration, it is recommend to replace the 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.