9.5x19.5x.75 actual size (10 x 20 x 1 nominal size). Our 10x20x1 air filter is an extended surface pleated filter, which outperforms standard air filters with medium efficiency, and are built for lower pressure drop, and extended service life, which reduces HVAC equipment maintenance and energy costs. The 10x20x1 air filter is measured to ASHRAE test standards 52.2, which establishes that the air filter will capture particulate as good or better than original manufacturer 10x20x1 air filters. Pleated design. MERV tested to ASHRAE standards. 410 cfm flow rate.