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Air Filters Delivered

4.5 (123)

21x21x1 Aerostar Air Filter

Name: Air Filters Delivered 21x21x1 Aerostar Air Filter - 21x21x1 Aerostar Air Filter
Brand: Air Filters Delivered
SKU: 41902212382874
Price: 69.36 USD
Availability: InStock
Rating: 4.5556 (3 reviews)

4.5 (1,234)

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Square 21x21x1 returns are uncommon enough that you've probably struggled to find this size at a hardware store. This Aerostar measures 20 7/8" x 20 7/8" x 3/4" actual, sized for a nominal 21x21x1 slot. Pleated synthetic media construction ...

Reviews

4.6

9 ratings

The Only Way to Buy Filters!

Lucky me! I have an air handler that takes a weird size filter. I learned years ago to not spend one minute looking in a hardware or big box store for these. I order them once a year and they show up within days! I'm very happy with the filters and the speedy service.

Lee · April 3, 2026