Filters-NOW DPFR20X25X5OB=DAR 20x25x5 MERV 13 Armstrong Air Carbon Odor Filter Pack of - 2 Nominal size 20 x 25 x 5 (Actual size 19 3/4 x 24 1/8 x 4 3/4) Carbon impregnated disposable pleated panel filters. A simple solution for controlling both odors and dust particles! Odorous gases and vapors are attracted to and held by the unique properties of the activated carbon material. Can be installed in virtually any HVAC system without modifications.