19.625X29.625X.75 actual size (20 x 30 x 1 nominal size). The 20x30x1 air filter is an extended surface pleated filter, which exceeds ordinary air filters with medium efficiency, and are engineered for decreased pressure drop, and increased service life, which reduces HVAC equipment maintenance and energy costs. The 20x30x1 air filter is classified to ASHRAE test standards 52.2, which establishes that the air filter will capture particulate as good or better than OEM 20x30x1 air filters. Pleated design. MERV classified to ASHRAE ratings. 1229 cfm flow rate.