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
Filtrete 20-in W x 20-in L x 1-in MERV 5 Basic Pleated Air Filter (3-Pack) in the Air Filters department at Lowes.com
Filtrete 20x20x1 Air Filter MPR 1500 MERV 12, Healthy Living Ultra Allergen, 2-Pack (exact dimensions 19.69x19.69x0.78) - Amazon.com