Filterbuy 13x20x1 Air Filter MERV 13 Optimal Smoke & Allergy Defense (4-Pack), Electrostatic Pleated HVAC AC Furnace Filters Replacement, Made in USA (Actual Size: 12.88 x 19.88 x 0.75)

I taped a single Merve13 filter to a 20" fan to build a free standing air filter. I also taped four, 5" X 20" X 20" Merv 13 together with a 20" fan to build a second free standing unit. Both cleaned the air in my 2,400 square foot house after a few minutes - checked it out with an air quality meter. Not much 'cleaning' difference in the two except the 5" one with a much greater filter area will last much longer before it needs to be replaced. I have a 5' filter in my furnace as well and change it every 6 months, but it probably would easily last a year. After 6-months there is only very little residue on the filter.

Works very well. So far, happy with purchase.

My hvac uses the 14x24x1 filter size. Every other brand I would buy, did not fit correctly. I had to bend the corners to fit it in. But these are slightly smaller, and they fit perfectly.

Well made filters, unfortunately they are too restrictive for my system. I’ve bought Merv 5’s . Make sure to check what filters you’re system needs.

Excelente filtro