HVAC Furnace Twin Media Filter With Internal Frame, All Air Goes Thru Filter For larger 20 x 30 x 1 inch furnace filter slots, install the Safe Home TM air purification filter. Not only removes allergens but also removes odors and chemicals from air in homes or small businesses. This furnace air filter is 20 x 30 x by 1 inch thick. Note Check with your HVAC technician to verify that your system is able enough to handle the density of a MERV 8 filter before purchasing this or any other MERV 8 filter. Install this MERV 8 with Air Flow First Going through the White Media. Made in USA. The Duo furnace filters feature self sealing edges to maximize effectiveness at capturing allergens, odors, and chemical. Use for furnace filter slots, temporary needs, or custom sizes in air return grills. The Duo replaces any 1 thick home air filter in any location and can last up to 3 months. How does the Duo work? The polyester outer layers remove pollen, mold spores, and other common allergens. The inner layer features FormaldaSorb TM and activated carbon that traps a variety of odors and hazardous gasses, such as formaldehyde, ammonia, and others that are emitted by cleaning chemicals, paint, particle board, and other household items. No other filters are as effective at removing dust mites, mold spores, pollen, odors, cleaning chemicals, ozone, paint fumes, and common gasses like formaldehyde which triggers asthma and allergies. Safe Home TM Duo Filter Features Dimensions 20 x 30 x 1 Captures up to 95% of common household allergens Eliminates odors from pets, paint, cooking, and more Uses high density carbon and advanced compounds FormaldaSorb TM , a patented potassium permanganate product plus the activated carbon in the second layer of the filter trap gasses that can cause health issues. Highly effective and affordable. Twin filter pad MERV 8 polyester white ASHRAE rated allergen filter plus an industrial chemical and odor filter, i.e. the activate