15.5625X24.5625X.75 actual size (16 x 25 x 1 nominal size). This 16x25x1 air filter is an extended surface pleated filter, which outpaces standard air filters with medium efficiency, and are built for decreased pressure drop, and longer service life, which reduces HVAC equipment maintenance and energy expenses. The 16x25x1 air filter is classified to ASHRAE test standards 52.2, which ensures that the air filter will perform as good or better than OEM 16x25x1 air filters. Pleated design. MERV rated to ASHRAE grades. 836 cfm flow rate.