Description
Actual size is 20.75 x 20.75 x 4.38. Accumulair brand 21x21x4.5 Rheem PD540018 substitute whole house air filters, exactly built to replace original manufacturer Rheem PD540018 air filters. Fully constructed so no forming or combs required. MERV classified to ASHRAE specifications establishing operation equal to the OEM Rheem PD540018 filters. Note: Sample filter picture shown is not the actual dimensions and is displayed for style purposes only. OEM names and Rheem PD540018 P/N used for filter replacement purposes only.