Purolator PuroGreen 20x22x1 Merv 13 Pleated AC Filters and Furnace Filters High Dust Holding Capacity Actual Size: 19-3/4 x 21-3/4 x 3/4 $8.98 Each - 1 Case of 12 Total $107.76 The Purolator PuroGreen M-13 Provides 90-93% Average Arrestance and Maximizes Dust Retention Capabilities