11.5x24.5x.75 actual size (12 x 25 x 1 nominal size). This 12x25x1 air filter is an extended surface pleated filter, which outpaces ordinary air filters with medium efficiency, and are designed for decreased pressure drop, and long service life, which reduces HVAC equipment maintenance and energy costs. This 12x25x1 air filter is graded to ASHRAE test standards 52.2, which ensures that the air filter will perform as good or better than original brand 12x25x1 air filters. Pleated design. MERV classified to ASHRAE classifications. 615 cfm flow rate.