The Flanders High Efficiency HDR Air Cleaner achieves high efficiency at low pressure drop. This proprietary media combines with AAF Flanders' unique V-pleat manufacturing design to give you the highest performance pleat available on the market today. Available in 5-inch sizes and designed to fit in 1-inch wall and ceiling returns (with available duct clearance). The deep V-pleated panel filter offers a larger surface area for catching impurities and reducing air resistance. The MERV (Minimum Efficiency Reporting Value) 8 rating means it is third-party certified to effectively reduce common indoor air pollutants such as household dust, pollen, dander, and lint. MERV ratings provide a standard comparison of air filter performance. A higher MERV rating signifies greater efficiency and increased protection against airborne particles. The clay-coated filter frame and wire backing provide durability throughout the filter's life. The Flanders High Efficiency HDR Air Cleaner maintains the minimum listed efficiency throughout the one-year life of the filter. UL Classified.