Description
Actual Size: 20.75 x 20.75 x 4.38. Accumulair brand: 21x21x4.5 Ruud PD540018 compatible whole house air filters, specifically constructed to replace original brand Ruud PD540018 filters. Fully box-formed with no forming or combs needed. MERV classified to ASHRAE 52.2 test standards establishing particle filtration as good or better than the original brand Ruud PD540018 filters. Note: The example filter pic displayed is not the actual dimensions and is displayed for design purposes. Company names and Ruud PD540018 P/N are included for filter style purposes.