[Perfect Compatibility] - 2 pack replacement filters compatible ONLY with Blue Pure 511 Air Purifier. Confirm your air purifier model and filter dimensions before purchase. 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. This replacement filter for the 511 air purifier features an advanced low-energy consumption design with a lower density structure, enabling higher efficiency, reduced airflow resistance, maximum filtration performance, and extended lifespan. [High Efficiency Filtration] - The Blue Pure 511 replacement filter includes a dual-layer 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 effectively reduces household odors from pets, cooking, smoke, wildfires, and volatile organic compounds (VOCs), promoting a fresher and cleaner 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. The built-in pull tabs allow for quick and tool-free removal and installation. Color: White Material: Filter Paper Package Contents: 2 x 511 Replacement Filters Note: Light reflection and display settings may cause slight color variations between the image and the actual item. Measurement tolerance: +/- 1-3 cm.