Important Note: Almost ALL furnace filters have a different actual size than the nominal size printed on the air conditioner filter. It's best if you measure your air filter for the EXACT size and compare it to our actual size - and then you can be sure your A/C air filter fits! With the 4in and 5in air filters there is a wider variance between the nominal and actual size depending on the manufacturer. If you are replacing a 4-3/8 depth 16x25x4 filter in your Honeywell unit you should order our 16x25x5 Honeywell Replacement air filter that measures 15-3/4 x 24-3/4 x 4-3/8 15.75x24.75x4.38. Nordic Pure 16x25x4 Pleated Air Filters MERV 8 are made of electrostatically charged synthetic materials that attract and capture most airborne particulates in your home. Each time air passes through a Nordic Pure pleated furnace filter, lint, household dust, pollen, dust mites, pet dander, bacteria, mold spores and other contaminants are removed. All Nordic Pure pleated air filters are manufactured using a heavy duty, moisture resistant beverage board frame. There is a metal mesh support grid bonded to the pleats for extra support. Our AC filter media prevents the growth of bacteria or mold, resulting in a much healthier living environment. MERV 8 furnace air cmore...Removes lint, dust, pollen, bacteria, pet dander, dust mites, mold spores and other contaminantsIf you are replacing a Honeywell or Lennox 16x25x4 or an air filter with an MPR rating with an actual depth of 4-3/8, please see our 16x25x5 (4 3/8 actual depth)Hypoallergenic, antimicrobial, and electrostatic filter media. Moisture resistant frame.Nordic Pure MERV 8 is equivalent to MPR 800Nominal Size: 16 x 25 x 4, Actual Size: 15-1/2 x 24-1/2 x 3-5/8 (15.5 x 24.5 x 3.63)Measure your air filter for the exact size and compare it to our actual size to ensure proper fit.Made with MERV rated synthetic poly blend pleated mediaNordic Pure recommends changing 4" air filters every 3-6 months