13.5625X23.5X.75 actual size (14 x 24 x 1 nominal size). This 14x24x1 air filter is an extended surface pleated filter, which outperforms standard air filters with medium efficiency, and are built for decreased pressure drop, and increased service life, which reduces HVAC equipment maintenance and energy expenses. The 14x24x1 air filter is classified to ASHRAE test standards 52.2, which assures that the air filter will perform as good or better than original manufacturer 14x24x1 air filters. Pleated design. MERV rated to ASHRAE grades. 688 cfm flow rate.