20 x 25 x 1 - Dynamic Air Cleaner Replacement # C3P2025 Filter Pads , (3) Pack Genuine Dynamic Polarized Media Pads , DON'T SETTLE FOR KNOCK-OFFS! Use with 20" x 25" x 1" 24 Volt Electronic Air Cleaners , Approximate Pad Size: 18-1/2 x 22-1/2 97% Efficient for particles down to 0.3 microns in size , Includes Activated Carbon Center Screen for Odor Control NOTE: White or Blue coloring of pads is simply different dye colors. There is no difference in performance or quality. Dynamic Air Filters Replace Many Comparable Air Cleaners & Air Filters: Aeriale Air Cleaner AirRanger AlpinePure ET Clean Air Defense EarthPure Electro-Breeze Electro-Filter EnviroSept Garrison Air Cleaners MicroGuardian AirScrubber III Natures Home MicroPower Guard Nature's Home One Hour Xenon MicroPower Guard Diamond Perfect Air Plus Premier One Pristine Air PurePak Pure Pak SolaceAir SpacePak Space Pak StratosAire Water Furnace and others. DO NOT MEASURE THE FILTER MEDIA ITSELF. There is a label right on the black plastic part at the top near where the power supply plugs in. Can't find it? Look inside the track of the black plastic part. This label gives the dimensions to order by. Can't find a label? Measure the entire air cleaner end-to-end and top-to-bottom including the entire frame and black plastic part at the top. DO NOT MEASURE THE FILTER PAD ITSELF. Replacement Media Pads Only , NO FRAME INCLUDED