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11.5x21x4 Air Filter Merv 8 11.5x21x4 Air Filter Merv 8
11.5x21x4 AC Filter Merv 11 11.5x21x4 AC Filter Merv 11
11.5x21x4 Furnace Filter Merv 13 11.5x21x4 Furnace Filter Merv 13
11.5x21x4 Filter Merv 13 Titanium 11.5x21x4 Filter Merv 13 Titanium
11.5x21x4 Filter Merv 10 Carbon 11.5x21x4 Filter Merv 10 Carbon
11.5x21x4 Filter Merv 8 Carbon 11.5x21x4 Filter Merv 8 Carbon

Similar sizes

Protects All Against
  • Pollen protection
    Pollen
  • Dust protection
    Dust
  • Mold protection
    Mold
  • Dust Mites protection
    Dust Mites
  • Bacteria protection
    Bacteria
  • Pet Dander protection
    Pet Dander
  • Smoke protection
    Smoke
  • Viruses protection
    Viruses
  • Cooking Smoke protection
    Cooking
  • Odor protection
    Odor
  • Smog protection
    Smog
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11.5x21x4 Air Filter

AC Furnace Air Filter 11.5x21x4 -Inches

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1. Select Filter Quality

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MERV 8
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merv-13
Better
MERV 13

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Product Description

Item Model Number: FKFB11.5X21X4A
Brand: Filter King
Filter size: 11.5x21x4
Actual Size: 11.5 x 21 x 3.75
4-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?

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In comparison to fiberglass filters, 11.5x21x4 pleated air filters are at least 20 times more effective. All Filter King air filters are made in the US.

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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.

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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.

11.5x21x4 Air Filter Reviews

What MERV Rating should I choose?

How Often to Change Your 11.5x21x4 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.