21 Inch Width

Glasfloss ZL 21x21x1 MERV 10 (FPR 5-6) AC Furnace Air Filters. (Box of 6). Actual Size: 20-7/8 x 20-7/8 x 7/8

Actual Size: 20-7/8 x 20-7/8 x 7/8 | Nominal Size: 21 x 21 x 1 Filtration Rating: MERV 10. Comparable to MPR rating 600 to 800, or FPR 5-6 rating. Improved MERV 10 Filtration with similar air flow and resistance as a MERV 8 filter. Durable & Long...

Glasfloss ZL 20x21x1 MERV 10 (FPR 5-6) AC Furnace Air Filters. (Box of 6). Actual Size: 19-1/2 x 20-1/2 x 7/8

Actual Size: 19-1/2 x 20-1/2 x 7/8 | Nominal Size: 20 x 21 x 1 Filtration Rating: MERV 10. Comparable to MPR rating 600 to 800, or FPR 5-6 rating. Improved MERV 10 Filtration with similar air flow and resistance as a MERV 8 filter. Durable & Long...

Glasfloss ZL 17.5x21x1 MERV 10 (FPR 5-6) AC Furnace Air Filters. (Box of 6). Actual Size: 17-1/2 x 21 x 7/8

Actual Size: 17-1/2 x 21 x 7/8 | Nominal Size: 17.5 x 21 x 1 ? Filtration Rating: MERV 10. Comparable to MPR rating 600 to 800, or FPR 5-6 rating. Improved MERV 10 Filtration with similar air flow and resistance as a MERV 8 filter. Durable & Long...

Glasfloss ZL 13x21.5x1 MERV 10 (FPR 5-6) AC Furnace Air Filters. (Box of 6). Actual Size: 12-7/8 x 21-1/2 x 7/8

Actual Size: 12-7/8 x 21-1/2 x 7/8 | Nominal Size: 13 x 21.5 x 1 Filtration Rating: MERV 10. Comparable to MPR rating 600 to 800, or FPR 5-6 rating. Improved MERV 10 Filtration with similar air flow and resistance as a MERV 8 filter. Durable & Long...