20" x 21" x 1" MERV 4 - Residential Washable Air Filter Residential Washable Air Filter:20" x 21" x 1" MERV 4 - Residential Washable Air Filter 20" x 36" x 2"

20" x 36" x 2" MERV 4 - Residential Washable Air Filter - 1 Pack

10" x 18" x 1" MERV 4 - Residential Washable Air Filter - 1 Pack

12" x 30" x 1" MERV 6 - Fiberglass Air Filter - 6 Pack

14" x 25" x 2" MERV 4 - Residential Washable Air Filter - 1 Pack

20" x 21" x 1" MERV 4 - Residential Washable Air Filter Residential Washable Air Filter:20" x 21" x 1" MERV 4 - Residential Washable Air Filter 20" x 36" x 2"20" x 21" x 1" MERV 4 Residential Washable Air Filter 1 Pack Actual Dimensions: 20" x 21" x 3 4 These quality filters are built to last a lifetime. They are interchangeable with 1" disposable filters and can be used again and again. The secret behind the filter's performance is its patented stage loading peak and valley design. Instead of face loading (particles captured on the outer surface of the filter) the filter uses stage loading, with each