Description
Actual Size: 20.75 x 20.75 x 4.38. Accumulair brand 21x21x4.5 Ruud PD540018 substitute whole house air filters, exactly engineered to be an alternative to the name brand Ruud PD540018 filters. Completely assembled with no forming or combs required. MERV classified to ASHRAE 52.2 test standards ensuring particulate capture to the level of the name brand Ruud PD540018 air filters. Photo: The sample filter pic shown is not true to size and is included to show style purposes. Brand names and Ruud PD540018 part numbers displayed for air filter style identification purposes only.