11.5X21.5X.75 actual size (12 x 22 x 1 nominal size). This 12x22x1 air filter is an extended surface pleated filter, which exceeds ordinary air filters with medium efficiency, and are built for decreased pressure drop, and long service life, which reduces HVAC equipment maintenance and energy expenses. Our 12x22x1 air filter is graded to ASHRAE test standards 52.2, which ensures that the air filter will filter as good or better than OEM 12x22x1 air filters. Pleated design. MERV tested to ASHRAE standards. 541 cfm flow rate.