They have the best quality plus made filters. All one needs is to order the correct size. I can see less accumulated dust. The filter I had wasn't collecting anything.
filter seem to work good but being 1/2 short makes it a bit hard to remove the filter i ordered 20 as needed new measures 19 1/2 but will need to change to 21 which will be 20 1/2 i guess and much easier to remove not sure why there made 1/2 inch short other brands are made to size
The fit was a little tight and had to push hard to get it in, I measured it against the original filter that came with the unit, and it didn't seem to be any difference in size. The original filter had metal frame so I wonder if that meant a closer tolerance, the Filterbuy filter is cardboard framed which by it's nature has a higher friction coefficient.