Filtrete 20-in W x 25-in L x 1-in MERV 11 1085 MPR Allergen Defense Extra Electrostatic Pleated Air Filter (4-Pack) in the Air Filters department at Lowes.com
3M Filtrete 20x25x1 Ultra Air Filter (6-Pack) - Walmart.com
3M Filtrete 20x25x1, AC/Furnace High Performance Air Filter, MPR 1900, Pack of 6 | eBay