rhey do a good job, i use them as a room filter the 20X20 fits a box fan and does as good of a job as the very expensive room filter machines.

These filters were a great price and a good rating for filters. I was looking all over and these were the best quality for a a great price.

good product and value

Recently my air conditioning unit had to serviced for maintenance. I was surprised when the technician offered to replace and install this filter for an exorbitant amount. Luckily, when the technician went to check the van for the filter, it was out of stock, so we couldn't get it done. Immediately, I started searching and found these filters. The quality is great and allegedly filters out many allergens. Depending on who you ask, this filter is a must have for many units or you can get by with high quality wall filters. I choose to have both filters, so I highly recommend purchasing these. There are different MERV values which determines the filteration, but these work for me and I keep them on my list for re-order. The only issue I have experienced is related to shipping/delivery. The first time it was delivered, the box was open and the filters were bent and damaged. Getting the replacement was easy and the next delivery was problem free. 5 stars for the product and value.

They fit but were smaller than advertised. They did not give a good seal some air was not filtered at all.

These are every bit as good as the filters supplied by the company that installed my heat pump, and certainly cheaper. The size is uncommon, at least as far as Lowes and Home Depot are concerned or I would buy there just to support local hardware businesses. Regardless, this product is indistinguishable to the naked eye from the OEM filter (probably made by the same manufacturer but I cannot be certain) that I substitute it for. And air quality seems just as good so I think it is doing an acceptable job.

Summary: I got the MERV 12 20x20x4 filter. It looks like it can do the job, but does not seem to remove any particulate matter from the air. In other words, it doesn't filter/clean the air at PM.5 and only marginally at PM2.5. Nearly any filter that is better than a dust filter will outperform this Nordic Pure filter.Details: I have 8 air cleaners in my home, including two BlueAir605 and Honewell HEPA and measure them regularly with a Dylos DC1700 particle counter. Two air cleaners that I use as supplemental are 20" box fans with 20x20x1 furnace filters. It's fire season with outdoor AQI at 63, but that doesn't really matter for this test. My wife burned her breakfast, so I took the "Nordic Pure 20x20x4 MERV 12 Pleated AC Furnace Air Filters 2 Pack" out of their box and coupled it with the fan. The ambient measurement in the room for .5PM was 27,000 particles in approximately .01 cubic foot of sampled air, which is about right. You can smell the burnt food. Also, on a day where the outdoor AQI is 150, this measurement can be similar to this reading (25,000 - 30,000). When I hold it to the Nordic Pure MERV 12, the .5PM measurement is essentially the same. In other words, it's not filtering anything at PM.5. I've never seen this before! Ever!! Especially for a MERV 12 filter!!! A MERV 8 can do much better than this!!!! I've done this experiment many times over the years.I have two filters next to me. They are not Nordic Pure, but a different brand: MERV 11 and MERV 14. Both the MERV 11 and MERV 14 showed commensurate reductions that were inline with their MERV rating, 24,000 and 21,000 respectively. That's about right for a smoky room. It won't go much lower in this situation because the air mixes so much, even if you hold it at zero inches. I later tested it against my HEPA filter and the reading went from 300 to nearly zero, so the meter is functioning correctly.If you have questions on the validity of this type of filter, please watch youtube video, Michigan Medicine, Dr. Jeffrey E. Terrell, director of the Michigan Sinus Center, "Build a do-it-yourself air purifier for about $25."On the slightly positive side, when the burnt smell was heavy, I did see a reduction in PM2.5 from 900 down to maybe 600 particles per .01 cubic foot of sampled air. Not great either, but at least it's doing something. I've seen MERV 8 filters perform much better than this.To be fair, I should mention that the measure of MERV 12 is more closely tied to PM2.5. It needs to show a reduction of PM1.0-3.0 80%-89.9%, 3.0-10.0 90% or greater. I'm measuring PM.5 because that's what we care about with wildfire smoke, the smaller particles; however, I will say that ALL of the other brands that I have worked with do a GREAT job with the smaller particles (PM.5), even one of a much lower MERV rating. This furnace filter should perform very well, especially because it is 4" thick, but it doesn't.The smoke is gone, and I did the experiments over again. The Nordic MERV12 didn't show any improvement in PM2.5 or PM.5. Ambient counts are 287 and 17 respectively. The other brand, MERV11 and MERV14, despite being only 1" thick, showed substantial improvement in both measurements. Even the MERV 11 filter cut PM2.5 counts in half. To give the 4" Nordic an edge, I sealed the areas between the fan and the filter; no improvement. Tried positioning the meter in different ways, no improvement.I've used another brand of 4" MERV 8 filter that worked really well; it was 20x24x4. That was the only size I could get, and it was 4" taller than the fan. It didn't matter. Worked great. I'm surprised that this Nordic Pure filter doesn't do much.Returning. Everything is sold out due to smoke and COVID, so I have few other options.About me: I have a technical background and own a Dylos DC1700 particle counter, which is the correct tool for measuring filter performance. Since 2016 I have been active in improving air quality in my house and have gone over to a few dozen different indoor environments during wildfire season to help my friends and a local school reduce their wildfire smoke exposure.My friend is in the HVAC business and manages a team that is responsible for a very large tech campus here in silicon valley. He is union trained with 20+ years of experience in commercial HVAC. I vet my work with him and we talk for hours on end about air filtration while using this particle counter.I enjoy working with my particle counter and use it sometimes every hour during California smoke season. I have fun adding air cleaners and filtration and tweaking everything to get low particle counts (clean air). The response of the meter is nearly immediate when you hold it in front of the air cleaner, so it can really show you what's going on by doing little experiments.

Size is good. About a 1/3 cheaper than other brand sold in store.

Les filtres m'apparaissent de bonne qualité. D'autre part sur le filtre on ne voit aucune d'indication qu'il s'agit d'un MERV 12. On aurait pu m'envoyer un MERV 8 ou MERV 11 sans que je le sache. Je n'ai aucune façon de faire la différence. Je veux bien faire confiance à AMAZON mais ça serait plus transparent si les filtres étaient identifiés correctement.

This is an excellent filter - it fits as well in our furnace as an OEM filter and seems to work fine. The price is very reasonable. The one improvement would be stamped tabs on one side of the filter that could be folded out to pull the filter from the filter compartment. The filter fits so tightly in our furnace that it is difficult to extract. I solve the problem by punching holes in one side and inserting twist ties to use as "handles" to pull it out. This takes just a few minutes, but a slight change in design (tabs) would make it work right out of the box.

I bought this filter to make a workshop air cleaner using a standard 20x20 box fan.In my use case, it works great: the built quality is great: the cardboard is sufficiently strong to allow the filter to be 'handled' and the wire meshing helps the filter keep it's form. As an air cleaner, it works well to eliminate any of the really tiny particulate

Second time I order them. Protects my heating system very well. Good packaging. Fabricated with great care. I will order them again.

great value - great filterreally happy with purchaseusing it with an extra filter 1" thick - so i can use this 20x20x4 one for a full year !