Flanders (4 Filters), 16" X 20" X 1" Precisionaire Nested Glass Air Filter - Walmart.com
HDX 16 in. x 20 in. x 1 in. Premium Pleated Air Filter FPR 10 HDX1P10-011620 - The Home Depot
PRO-SOURCE 16 x 20 x 1", MERV 10, 55% Efficiency, Wire-Backed Pleated Air Filter Synthetic, Paperboard Frame, 300 Max FPM, 825 CFM, High Capacity, Use with Any Unit PRO10444 - 00626325 - Penn Tool Co., Inc