[Perfect Compatibility] - 2 pack replacement filters ONLY compatible with Blue Pure 511 Air Purifier. Please confirm your air purifier model and filter dimensions before purchasing. Filter Height: 8.27in (21cm), Width: 7.87in (20cm). Note: Not compatible with 311 Auto, 411, 411i Max, 211i Max, 311i Max, or 311i+Max. [High Efficiency Filtration] - This replacement filter for Blue Pure 511 air purifier features a double-layer high-efficiency filtration system. The H13 True HEPA filter captures 99.97% of airborne particles as small as 0.3 microns, including pollen, dust, pet dander, and other allergens. The Activated Carbon Filter helps reduce household odors from pets, cooking, smoke, wildfires, and VOCs, promoting a fresher indoor environment. [Easy to Replace & Install] - Designed for convenience and cost efficiency. It is recommended to replace the filter every 6 months, depending on air quality and usage. Small tabs on the filter allow for easy removal and installation without tools. Color: White Material: Filter Paper Package Contents: 2 x Replacement Filters for Blue Pure 511 Only the above package content is included; other items are not part of this package. Note: Lighting and monitor settings may cause slight color variations between the image and the actual product. Measurement may vary by +/- 1-3cm.