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21.25x21.25x1 Air Filter Merv 8
21.25x21.25x1 AC Filter Merv 11
21.25x21.25x1 Furnace Filter Merv 13
21.25x21.25x1 Filter Merv 13 Titanium
21.25x21.25x1 Filter Merv 10 Carbon
21.25x21.25x1 Filter Merv 8 Carbon 21.25x21.25x1 Filter Merv 8 Carbon
Protects All Against
  • Pollen protection
  • Dust protection
  • Mold protection
  • Dust Mites protection
    Dust Mites
  • Bacteria protection
  • Pet Dander protection
    Pet Dander
  • Smoke protection
  • Viruses protection
  • Cooking Smoke protection
  • Odor protection
  • Smog protection
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21.25x21.25x1 Air Filter

AC Furnace Air Filter 21.25x21.25x1 -Inches

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Odor Eliminator

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Product Description

Item Model Number: FKFB21.25X21.25A
Brand: Filter King
Filter size: 21.25x21.25x1
Actual Size: 21.25 x 21.25 x .75
1-Inch Filter
MERV 8 Filter Rating
Protection From: Pollen, Dust, Mold, Dust Mites, Bacteria, Pet Dander, Smoke, Viruses
Residential / Commercial Use

Manufactured in the US

Why Buy Air Filters From Filter King?


In comparison to fiberglass filters, 21.25x21.25x1 pleated air filters are at least 20 times more effective. All Filter King air filters are made in the US.


Filters frames are made out of heat resistant paperboard with horizontal grid supports. Able to withstand temperatures of up to 200° F and resistant to moisture, the paperboard frames do not support microbial growth and outperforms traditional cardboard frames.


Chemical free, electrostatically charged synthetic polyester media is pleated, maximizing the surface area, to capture a high number of airborne particles as small as 0.3 microns with low air flow resistance. To increase durability, the media is supported with a corrosion resistant steel wire.

21.25x21.25x1 Air Filter Reviews

What MERV Rating should I choose?

How Often to Change Your 21.25x21.25x1 Air Filter?

Filter King AC & furnace filters aren’t the typical fiberglass filters that need to be replaced every 30 days. Our filters can typically be used for 3 to 5 months before requiring to be changed. Naturally, a variety of things influence filter lifespan.

Some of the factors that influence your filter’s life include outdoor air quality, whether pets are in the home, and how well your HVAC system is maintained.

Your air filter becomes clogged over time by trapped particles, preventing airflow. The efficiency of the HVAC filter declines. Your system must work harder to heat and cool your home. The extra strain on the HVAC system causes higher energy bills. Regular home air filter replacements can prevent expensive system repairs or replacements down the road.

You should change your filter more frequently if you notice:

  • Household dust build-up
  • The air isn’t cooling as is used to
  • There’s more dust near the air vents
  • A dirty filter surface
  • Higher energy bills
  • Burning smells near your HVAC system.

21.25x21.25x1 Air Filter

Filter King 21.25x21.25x1 size air filters are used by accompanying air systems to keep pumped in air clean. The filters consist of a tight mesh weaving designed to capture and absorb a range of irritants entering your home via airflow. Air filters work constantly as the air continues to come in, cycling fresh air throughout your home. The process raises your home’s indoor air quality and keeps the air coming in free of harmful particles. Your air filters become dirtier over time, and will eventually need replacement before they start causing problems.

When the air filters in your home become dirty, they end up causing several problems for their systems and your home. The dirty filters will block off airflow, which means that the air inside your home will be unable to cycle out leading to dryness and stagnation. Your air systems also face issues as they attempt to push airflow past the blockages and into your home. The efforts will lead to mechanical damage for your systems and a rise in energy billing over time.

The air systems in your home work best when the air they bring in is allowed through new air filters without any problems. We offer fresh, new 21.25x21.25x1 size air filters for sale at affordable prices and ready for use upon arrival. Filter King also has premium delivery services, with a subscription option to have new filters arrive at your home as often as monthly. Our filters rate as an eight on the MERV (Minimum Efficiency Reporting Value) scale. This means that they filter out particles like:

  • Pollen
  • Dust
  • Mold
  • Dust Mites
  • Bacteria
  • Pet Dander
  • Smoke
  • Viruses

21.25x21.25x1 Furnace Filters

Furnace air filters have the important function of cleaning up heated airflow passing through the system. The furnace air filters clean up heated airflow before its distribution, which prevents irritants from polluting your home. Over time, the furnace air filters in a system will become dirty and begin blocking the heated. The resulting rise in internal temperatures will cause mechanical damages and temperature fluctuations throughout your home. Order new air filters now and have them delivered promptly before easy installation.