They do not fit in the filter housings properly on ...
931859
They do not fit in the filter housings properly on a superduty Truck the orings are to big cost me a lift pump and two injectors never again
4974564
Don't buy these filters if you are to replace the  4CH-21 filters, these filters are wrong thread type and will not fit.
3037606
The filters do not fit my Roomba 650 series, I am having to reuse the original ones, the foam is so poorly fitted I cannot shut the Roomba to operate it.
4535459
These filters are over-sized compared to their measurements and compared to the filters they should replace.  The filters are about 1/2 inch longer than they should be and do not fit.  I've been buying replacement 20x25x5 filters for years and have never had any problem with the other filters marked as 20x25x5 and I use 3 each time I replace my filters so I have replaced quite a few of them.  I now need to buy other 20x25x5 filters and I will never buy the Nordic Pure filters again.  What good is a filter 1/2 to long to fit?
4054530
The air filter is too tall to fit into the air cleaner housing properly. I wish I would have looked at return policy sooner, since it will be tossed. Not happy
816746
It seems filter elements work fine.  However, keep your original filter surround/spacer AND DO NOT THROW AWAY like I did or else items will not fit snugly with your filter system and you may either have to return them or do just like what I did and hold them up with a tape before closing the back cover or your filter unit.
3090349
The 14x20x1 measurement is inaccurate. I have overhead return vents and these do not fit as snugly as other brands. The filters are too loose and therefore they make a loud noise either getting sucked up into the vent or falling out when the air kicks on/off. I've used other brands in the past and never had this problem but decided to try these due to price and convenience. I've already purchased a different brand in less than a month in order to avoid this annoyance.
1356935
These are not direct fit. I had to custom make my own bracket to be able to use these.
4074574
Check your length - these filters are about 3/4" longer than most and don't fit my Trion enclosure. I ordered these replacements when I used the last of my previous batch (3 months ago). Lo and behold,  returns are only allowed within the first month. Not happy - live and learn.
97421
Filters are difficult to remove.  They appear to be intended for single use, rather than reusable in the way the original is.
1054604
filter is bigger than plastic frame it should fit in, about 1/8" on each side. I was able to push it in but As a result some sides got jammed creating ugly gaps for air bypass the filter.
2043001
Not a fan. The filters do not fit my roomba. I have to physically manipulate them to fit. The price is right, but not if it means sacrificing quality materials. Hoping another seller has better accessories for sale.
533585
Filters are listed as 20x27x1 (Actual Size). They are in fact 20 1/16 x 27 1/8, therefore I had to smash them to make them fit. When I pay $77.00 for a quantity of four filters I expect them to be the size stated. Normally filters are slightly smaller than stated size and that allows them to fit snug. If they're too big, they just don't fit. Very disappointed that I literally have to ruin them to make them to be able to use them.
1667868
Item looked similar to my original filter, but in the end - it didn't fit in all the way.  Then they made ME pay for return shipping. It's not my fault it doesn't fit. that really makes me mad!!
4788932
One of the two filters leaked badly the first time I installed it.  I had to remove it and re-install it 3 times before it sealed up properly.  The second filter fit fine.
3074330
These are about 1/8" longer and wider than every other universal/standard filter cartridge I've ever purchased. Unusable for me as my filter housing would not fully seat.
826235
The Grease Filters (2) look like the original filters, but I can only guess they are a little smaller, as they will not stay in the grooves set for the filters. Which makes them defective for my purpose. Not sure what to do. I am not going to pay shipping to send them back. Suggestions? I am really unhappy as I need filters under the cabinet of the microwave to use it.  Rene' Domme