Actual size is 20.75 x 24.25 x 4.38. Accumulair brand 21x24x4.5 Ruud Protech 540020 substitute whole house air filters, specifically constructed to substitute for the name brand Ruud Protech 540020 air filters. Completely assembled so no assembly or combs required. MERV rated to ASHRAE 52.2 test specifications ensuring performance equal to the OEM Ruud Protech 540020 air filter. Notice: Sample air filter pic shown is not the actual dimensions and is there to show style purposes. Company names and Ruud Protech 540020 identifier are listed for air filter substitution identification.
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