Top positive review
Ignore Any Horror Stories, Actual Info About This Filter and Filters In General UPDATE APR 2019
September 29, 2018
SEE UPDATE BELOW
NOTE: I have used these filters for over 7 years Filtrete Clean Living Basic Dust AC Furnace Air Filter, MPR 300, 20 x 25 x 1-Inches, 6-Pack with no problems and I keep my fan on my HVAC on 24/7 which reduces hot/cold spots and results in less dust but it means you have to change your filter more frequently but with 3 dogs in addition to the normal dust/dirt/lint they still last 4-6 weeks easy. I have reviewed other brands for Amazon and none work any better, most worse and no real cost saving on any of them.
I was not going to write a review of this but after reading some of the other reviews it seemed like there was a big lack of knowledge about these filters. Let me start with the photos that people have posted (not sure if everyone's page looks like mine, should be off to the right side) and you can see one of the filters shown has a latticework design to hold/support the filter, what you may not realize is that you have essentially blocked at least 10% of your filter with that latticework, another filter shows it torn up and even a glance indicates it was inserted upside down (these filters are 1 way devices, hence the arrows on the sides showing airflow PLUS if inserted correctly the wire mesh would prevent this from happening under any circumstance). I also read about this filter being too hard on a unit... uh this is the bottom line of these filters with the least resistance to airflow and if they are hard on your unit, you may have a cheap unit or a fan about to die. I was particularly boggled by the one where the filter turned black, stopped up and collapsed and the reviewer blamed the filter ....... sounds like some serious and possibly dangerous air quality problems that need attention quickly, this is NOT a filter problem, possibly a furnace problem. As far as the thickness of material used 5 years ago vs what is used today, the thickness means nothing, it is the permeability of the material to block passage of dust/dirt and other things harmful to the unit and yes Virginia they have actually made the filter better over 5 years and probably saved themselves some money in the process. Don't lose sight of the big picture, "Does it filter as it should and have the strength to hold up?" the answer is yes, I don't care how much profit they made as long as I can buy them at a fair price in comparison to other filters and they actually do the job they promised to do (also a yes) while meeting the MPR 300 specification which is approximately equivalent to a MERV 7 (still a yes).
I should note that several people mentioned the filter "bowing" when under pressure, mine stays bowed since I run my fan 24/7 and none have ever failed in 7+ years, it can flex which means it is actually less likely to break apart. The "bowing" is not a sign of failure and if it actually did come loose it would mean you have either the wrong size filter or a defective bracket in your unit since the cardboard frame remains rigid.
UPDATE: I needed to add that IF you let your filter go without replacement for much longer than its intended life and it gets so dirty it cannot pass air it can actually bow to the point it can break loose, you have to really ignore it for a LONG time and have enough trash/dirt to prevent airflow, this is a rare occurrence but I thought I should mention it. These type filters are meant to be replaced on a regular basis.
I saw no reason to take a picture of my dirty filter but it catches all the dog hair and during shedding seasons I might have to change it in 4 weeks but usually they last for about 6 weeks, I have another home in the country and those last closer to 8 weeks (which concerns me a bit about air quality in the city).
I should mention that if you had your fly-by-night installer put in a "cheaper than dirt" system the list of possible problems is endless and they are never going to come back and say "it was the cheap system I installed" or "I installed it incorrectly" and the filter is always an easy target. Sadly life tends to lean towards the maxim of "You get what you pay for"
Bottom Line: Ignore the horror stories, I have had many talks with several HVAC techs and the one thing they do all agree on is this:
Unless you have a real need for high levels of filtering (severe allergy etc) use the filter with the least resistance that will block damaging dirt and dust from your unit (that would be this filter) and any higher level of filtering will probably shorten the life of your unit and can make the likelihood of the unit freezing up in the summer more likely due to reduced airflow over the coils. 4 Stars instead of 5 mainly because the shipping packaging seems to be a crap shoot, most times they arrive perfect but I have had several delivered where the filters were near unusable due to being crushed in a inadequate shipping box that lacked protection.