4" MERV 8 Furnace & AC Air Filter by Filters Fast® - 3-Pack
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4" MERV 8 Furnace & AC Air Filter by Filters Fast® - 3-Pack


Only $23.98 per Filter
Retail: $89.99 /ea
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Retail: $89.99
You Save: 20%
FF4M8 Sizes :
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The 4" MERV 8 Furnace & AC Air Filter by Filters Fast® - 3-Pack is a set of MERV 8 filters that effectively reduces contaminants from your indoor air. Removing these airborne particles can help improve allergies and alleviate sinus irritation that can cause watery eyes, itchy throat, coughing, and sneezing. The MERV 8 filter media is electrostatically charged and constructed with spun micro-fiber that also will not retain moisture, which can lead to microbial growth. Aside from the health benefits, these HVAC filters will also extend the life of your heating and cooling system by making it work more efficiently.

Note: These filters do not contain fiberglass.


  • Brand: Filters Fast®
  • Part Number: FF4M8
  • Pack Size: 3
  • Filter Life: 6 - 12 Months
  • MERV Rating: 8
  • Filter Type: Electrostatic pleated
  • Material: Synthetic
  • For commercial and residential use

Available Sizes:

The 4" MERV 8 Furnace & AC Air Filter by Filters Fast® is available in the following sizes:

Nominal Size Actual Size Alternate Part Number
12x24x4 Air Filter 11.375x23.375x3.625 PF8.0412243PFF
16x20x4 Air Filter 15.375x19.375x3.625 PF8.0416203PFF
16x25x4 Air Filter 15.375x24.375x3.625 PF8.0416253PFF
18x24x4 Air Filter 17.375x23.375x3.625 PF8.0418243PFF
20x20x4 Air Filter 19.375x19.375x3.625 PF8.0420203PFF
20x24x4 Air Filter 19.375x23.375x3.625 PF8.0420243PFF
20x25x4 Air Filter 19.375x24.375x3.625 PF8.0420253PFF
24x24x4 Air Filter 23.375x23.375x3.625 PF8.0424243PFF
25x29x4 Air Filter 24.375x28.375x3.625 PF8.0425293PFF

Custom Sizes:

  • If you don' t see your size, order a custom made air filter! Custom made air filters do not come individually wrapped.

How do you install the 4" MERV 8 Furnace & AC Air Filter by Filters Fast®?

  1. Once your air filters arrive, gather your supplies including a ladder (if needed,) safety goggles, gloves, a mask, and a disposable bag.
  2. Remove the metal grate from your air return.
  3. Carefully remove the used air filter and place it immediately and gently into the disposable bag. Then tie the bag sealed.
  4. Place the new air filter in place of the filter you just removed and replace the metal grille.

How often should you replace the 4" MERV 8 Furnace & AC Air Filter by Filters Fast®?

  • Changing your 4" MERV 8 Furnace & AC Air Filter by Filters Fast® is a very quick and easy process that should be done once every six to twelve months.

What contaminants does the 4" MERV 8 Furnace & AC Air Filter by Filters Fast® reduce?

  • The 4" MERV 8 Furnace & AC Air Filter by Filters Fast® is a MERV 8 air filter, which means that it reduces the following contaminants:

    • Dust
    • Pollen
    • Mold Spores
    • Other Common Airborne Allergens

Compatible Models:

The 4" MERV 8 Furnace & AC Air Filter by Filters Fast® - 3-Pack is correct replacement for the following model numbers:

BrandModel NumberDescription
GeneralAire GENERALAIRE 5FM2025 Air Cleaner filter media
GeneralAire GENERALAIRE MAC2000 Air Cleaner filter media
GeneralAire TRION 255649-102 Air Cleaner filter media
No results for {X}

Reviews from Trustpilot

Customer Reviews:

Total Reviews: 48 Average Rating: 4.55 / 5.0

Valued Customer2023-08-29

My alegeries decreased immediately as soon as the first filter was installed, I have been using this filter since 2007 when I had a new AC installed.

Collected by Trustpilot.com
Steven Cahn2023-07-23

I've been using them for a few years now and find them reliable and consistent. They perform to specifications, as far as I can tell.

Collected by Trustpilot.com
Orlan Gessford2023-07-16

Like the product and will continue to buy in the future.

Collected by Trustpilot.com
Dorothy Ann2023-06-23

The 4" measurement in 16x4x25 MERV 8, was more nearly 3 and 3/4" It should be OK. The one I was replacing, a Honeywell MERV 11, was 4 and 3/16" ,which was very tight and hard to remove.

Collected by Trustpilot.com
KHIN TINT2023-06-07

Convenient, easy to use, and affordable during the inflation and politically challenging period.

Collected by Trustpilot.com
Joann H.2023-06-02

Wonderful product

Collected by Trustpilot.com
Louise Anderson2023-05-25

Fits and works very good. Easy to order. I will be ordering again

Collected by Trustpilot.com
Norman Pieschalski2023-05-05

The product works well. I am very happy for purchasing this product. It keeps the warm air clean. My ONE HOUR HEATING AND COOLING workers tell me it's good product.

Collected by Trustpilot.com
Rick Greb2023-04-10

Filters are cheaper than purchasing from heating and air conditioning company.

Collected by Trustpilot.com

Great value. Works well.

Collected by Trustpilot.com
Mark N.2023-03-03

Good price good quality.

Collected by Trustpilot.com
TOM K2023-02-18

great quality and a great price.

Collected by Trustpilot.com
JIm GLASS2023-02-17

It’s a filter. Build seems good quality, and it does its job.

Collected by Trustpilot.com
ROBIN DODD2023-02-03

Great products, great prices. Love. Their reminder program!

Collected by Trustpilot.com
Regina Oryszczak2023-01-09

Just started using on HVAC tech's recommendation in lieu of the 1 inch.

Collected by Trustpilot.com

Have used these the past 5 years with great results. Competitive pricing and fast shipping.

Collected by Trustpilot.com
constance Kiefiuk2022-11-06

great value for the price and fast delivery.

Collected by Trustpilot.com
Norman Pieschalski2022-11-05

So far so good. But I'm waiting for the cold weather to determine quality. More to come.

Collected by Trustpilot.com

The quality of the product is good as is the price.

Collected by Trustpilot.com
New customer2022-08-11

I have a large openning on my HVAC and so need the 4inch size. MERV 8 work great to filter the air.

Collected by Trustpilot.com

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