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21x21x4 Air Filters

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$22.87 Price Per Filter

Product Description

Filter Size: 21x21x4

Actual Size: 20.5x20.5x4

Actual Size Fraction : 20.5x20.5x4

21x21x4 Air Filters

21x21x4 Air Filters

$22.87 Price Per Filter
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Choosing the Right MERV for your AC and Furnace Air Filter

As important as the right size is the appropriate MERV for your health needs and HVAC equipment capacity. Unless you are dealing with serious health conditions, you need very basic information to choose the best MERV rating for your needs.

In short, the best MERV rating for houses or businesses is the combination of exposure to airborne pollutants/ health needs and your HVAC equipment's capacity (provided by the manufacturer). 

Here is an easy chart with the airborne pollutants filtered by MERV 8, 11, and 13 air filters. If you need more in-depth information about what the best MERV rating is for your household or business, our MERV Rating Explained guide has all the answers.