The Mann Hummel MERV 8-rated electrostatically charged medium efficiency air filters offer you the protection needed from airborne particles and contaminants while improving the air quality for your residential or commercial applications. With the MERV 8 extremely low-pressure drop and high dust holding capacity, these filters are great for your utilization to supply your home or business with the air quality you wish for while optimizing the performance and longevity of your HVAC unit. Constructed from a two-piece frame provides rigidity and durability with double-wall thickness around the outer edge. Independently tested and verified for quality control (comparable with MPR 600). 100% synthetic, proprietary media withstands moisture and damage. Rust-resistant, expanded metal support grid made of galvanized steel. Industry-standard suggests to replace filters at least every 3 months