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Filters Fast - Filter. Purify. Protect.

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

FF4M8

$71.95
Only $23.98 per Filter
Retail: $89.99 /ea
You Save: 20%
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$71.95
Retail: $89.99
You Save: 20%
FF4M8 Sizes :
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Frequently Bought With This Item

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.

Specifications:

  • 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 19.5x24.5x3.625 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 Parts:

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

Part Number
FF4M8-12244
FF4M8-16204
FF4M8-16254
FF4M8-18244
FF4M8-20204
FF4M8-20244
FF4M8-20254
FF4M8-24244
FF4M8-25294
FFM8PLEAT 4-12244
FFM8PLEAT 4-16204
FFM8PLEAT 4-16254
FFM8PLEAT 4-18244
FFM8PLEAT 4-20204
FFM8PLEAT 4-20244
FFM8PLEAT 4-20254
FFM8PLEAT 4-24244
FFM8PLEAT612244
FFM8PLEAT616204
FFM8PLEAT616254
FFM8PLEAT618244
FFM8PLEAT620204
FFM8PLEAT620244
FFM8PLEAT620254
FFM8PLEAT624244
PF8.0412243PFF
PF8.0416203PFF
PF8.0416253PFF
PF8.0418243PFF
PF8.0420203PFF
PF8.0420243PFF
PF8.0420253PFF
PF8.0424243PFF
PF8.0425293PFF
No results for {X}

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 GENERALAIR TERSUS 2000 AIR PURIFICATION SYSTEMS AC Filters
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}

Customer Reviews:

Total Reviews: 78 Average Rating: 4.5 / 5.0

Filtersfast Reviews on Trust Pilot external site
Welda Lynn2026-06-02

These are the best AC filters. My AC man highly recommend them .

Collected by Trustpilot.com
Antwine Jefferson2026-05-18

Well manufactured product.

Collected by Trustpilot.com
Vivek Lakhi2026-03-29

Although the purchased size was identical to other brands (20 x 20 x 4), the actual size of the filter was about a 1/4 to 1/2 inch smaller in all directions. It seems misleading to round up the size in the advertising. There is a gap around the filter that will allow a small bit of unfiltered air to pass through to the HVAC and reduce the effectiveness of the filter. I will use these up, but will not be buying them again. It's too bad because the filter itself and construction seem decent, but the skimped size makes it not worthwhile or effective.

Collected by Trustpilot.com
customer2026-03-20

It arrived on time and in good condition and fit our furnace.

Collected by Trustpilot.com
customer2026-01-30

Tried to save some money by buying the generic “Filters Fast” brand 20”x25”x4” filter to replace my Honeywell filter, also 20” x 25” x 4”, and it’s the wrong size! Don’t market it as a replacement product if it’s not equivalent!!! How was I supposed to know the actual dimensions were different than the size advertised? The actual size is not listed when you're viewing the product. Very disappointed.

Collected by Trustpilot.com
Joe H.2026-01-26

These are exactly the same filters that the local HVAC company sells for 2x-3x the price. Also less expensive than the local HVAC supply company.

Collected by Trustpilot.com
customer2025-11-28

Wrong size.

Collected by Trustpilot.com
Richard S Weiner2025-11-01

Good pricing, good product, fast shipping.

Collected by Trustpilot.com
Mark N.2025-09-21

They fit well and do the job fine.

Collected by Trustpilot.com
Karen2025-09-09

I never ordered it to come so soon! I still have plenty. If you have me down as a subscriber, please take me off your lists.

Collected by Trustpilot.com
Bonnie Tarmann2025-09-01

The filters are a good price and arrived quickly.

Collected by Trustpilot.com
constance Kiefiuk2025-08-06

Great value, swift delivery.

Collected by Trustpilot.com
tony2025-08-03

exact fit and good price

Collected by Trustpilot.com
Carr2025-05-25

Easy to order!

Collected by Trustpilot.com
Dominic Rivas2025-05-19

The filter do a great job. Keep the dust levels low.

Collected by Trustpilot.com
Arthur Case2025-04-13

good value.

Collected by Trustpilot.com
Karen Burge Buelna2025-03-22

They fit perfectly and fast service

Collected by Trustpilot.com
customer2025-03-17

Would be better if the cost was reduced

Collected by Trustpilot.com
Joe H.2025-02-24

Great product. Exactly like the ones I used to buy at the HVAC supplier but a heck of a lot cheaper.

Collected by Trustpilot.com
Barbara Heath2025-02-17

They were exactly like the ones I buy in town, but I didn't have to go out

Collected by Trustpilot.com

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