Aerostar 20x20x2 MERV 13 - 6 Count - Pleated HVAC, Furnace & Air Conditioner Filters - Removes Bacteria, Dust, Cold & Flu Germs, Lint, Mold, Pet Dander, Allergy-Causing Pollen, Smog, Smoke & Viruses

Best filters I have found at a reasonable price to construct a home made box fan filter referred to as a Corsi-Rosenthal filter. Easy to make, couldn’t be easier to use, works extremely well.

Fits in air conditioning

These work and fit as advertised, fast delivery.

I brought it because it's value for money and that it's sold by Amazon. I actually don't exactly what that means.I suppose it's cost-saving by the manufacturer so there's nothing useful printed on the filter other than the direction of airflow. There's no MERV rating on it so they can use the same size cardboard frame for different MERV filters. But why there is no Aerostar on it and a made-in USA logo? But it's not only Aerostar. I have another brand doing the same thing. So I suspect that Aerostar orders the cardboard housing from somebody else, puts the filter in, and assembles it themselves. So I doubt if everything is made in USA.I'm making a box fan filter cube so I ordered the 2 in thick version, stronger to hold up the fan. The pleats are very unevenly spaced. But that should work normally. The thing is at the end of the pleats it's loose. I don't know how they do it but apparently, it's not securely glued on anything. I think it relies on the fact that if you blow air through the filter with a grid supporting the back, the air isn't going to leak through the edges. Probably it doesn't but I have no way to test it.In comparison, the HEPA filters for car cabins and for portable air purifiers are more rigid, with the pleads securely glued into the filter frame. Some pleads are rigid like plastic.

Seem to do a good job at keeping a lot of the dust from going through our ventilation system. Price was better than I could find locally. I replace it every three months.

I buy these pretty often and use them for a home air purifier. It's able to filter a huge amount of air in the home pretty effectively. It's wild how much these filters are able to catch, you can tell easily when swapping them out with the new filters. Great filters definitely worth it

This isn't my first purchase of these filters so I've had some experience with them and am I repeat customer. These 20x20x2 filters fit perfectly in my system. By perfect I mean there is a small gap on each side but not so much that air gets past them. Even if it did it would be such a small amount that it wouldn't make a big difference. I see other reviewers freaking out cause they aren't completely snug in their units but I don't see how this matters as typically there are ledges the filters sit on so air isn't going to pass through every inch of their filter space. Plus, having that gap makes it easier for replacement so you can actually grab a hold of them. They seem to do the job they were built for. I have two units in my house (4 zones) and replace one filter every 2 months and the other ever 4 - 6 months.I would purchase these again.

So I love these for making home made fan filters. The 2” thickness makes it sturdy and the 20x20 is the perfect size for box fans. The price is going up so that’s a bummer. But I take 4 of them and tape them together in a box formation and lay the box fan on top. The fan pulls air thru the filters and helps clean out the dander and dust from the house. After a couple months, It’s clearly evident how much it’s cleaning the air.