Sterling Seal DM-FI5257510288 Purolator Defiant Mark 80-D Extended Surface Pleated Air Filter, Mechanical Merv: 8, 20" W x 25" H x 4" D (Pack of 6) Mechanical MERV8 Filter Exceeds ASHRAE Standard 62 air cleaning specifications for filters installed upstream of cooling coils; Air Flow Capacity listed at 500FPM Low initial resistance for energy savings; Quality Engineered; Consistently Produced; Made of 100% synthetic Fibers; Made in the USA for over 30 years Two-Piece Frame Construction: will not rack, warp, or bend under normal handling or operating condition