Description
Actual size is 20.75 x 20.75 x 4.38. Brand: Accumulair. 21x21x4.5 Rheem Protech 540018 substitute whole house air filters, exactly engineered to replace the original manufacturer Rheem Protech 540018 air filters. Completely box-formed so no forming or combs needed. MERV graded to ASHRAE 52.2 test ratings establishing performance equal to the OEM Rheem Protech 540018 air filter. Photo: Sample filter pic as shown is not true to size and is included to show configuration purposes. OEM names and Rheem Protech 540018 part numbers are listed for air filter substitution identification use.