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Filter Size: 21x21x4
Actual Size: 20.5×20.5×4
Actual Size Fraction : 20-1/2×20-1/2×4
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Custom Filters Direct is your single leading source for high-quality air filters for a wide selection of applications, from home to office and commercial settings.
We have a massive selection of air filters in stock and ready to ship. Simply choose your filtration level and size.
MERV 8 filters: We stock a huge selection of MERV 8 filters. MERV 8 air filters are the perfect choice for your home?s air systems to clean up incoming airflow. A MERV 8 rated air filter will capture nearly 85 percent of particles between the sizes of 0.3 microns and 10 microns, making them a solid choice for most residential settings.
MERV 11 filters: A MERV 11 air filter will capture 85 percent or more of the particles between 0.3 microns and 10 microns, which is similar to what a MERV 8 air filter captures, but MERV 11 air filters also capture between 65 percent and 79 percent of smaller particles. For those with pets, MERV 11 filters provide superior protection and air quality, and they can also protect against smog, smoke, and automobile exhaust fumes.
MERV 13 filters: A MERV 13 air filter captures 90 percent or more of particles that are sized between 0.3 microns and 10 microns, making them the top choice for an air filter for those who are seeking superior air quality. MERV 13 air filters are the perfect choice for those who have newborn babies, who have lung diseases or compromised immune systems, and for those who need the top level of air filtration performance in business and medical care settings.