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Amazon.com: Filterbuy 20x20x1 Air Filter MERV 13 Optimal Defense (4-Pack), Pleated HVAC AC Furnace Air Filters Replacement (Actual Size: 19.50 x 19.50 x 0.75 Inches) : Tools & Home Improvement
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Filtrete 20-in W x 20-in L x 1-in MERV 13 1900 MPR Premium Allergen, Bacteria and Virus Electrostatic Pleated Air Filter in the Air Filters department at Lowes.com
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Pleated Furnace Filter, Ultra Allergen Reduction, 3-Month, Purple, 20x20x1-In. - Bradford, NH - Lumber Barn
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Filtrete by 3M 20x20x1, MERV 12, Advanced Allergen Reduction HVAC Furnace Air Filter, 1500 MPR, 4 Filters | Bigbigmart.com
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Homemade HEPA filter for tiny, dusty apartment. This is the result of 18” furnace HEPA filter + Box fan on about 10 hours per day for 1 month. Total price <$40; 6
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