Pleated Air Filters is Good ; We live in an area that we have to heat our rural mountain home from early September to May. We also heat with a Combo furnace that uses wood, anthracite coal or #2 oil. Our return duct requires two filters. 15 years ago I replaced the blower motor with an upgrade from 1/3 hp to a 1/2 hp motor to accommodate a higher rated merv filter from a spun fiberglass filter to a merv 11 particle filter. These filters seem to work well. They are stamped with the merv rating on the cardboard frames. Fit is slightly looser than the Filtrete filters but well within the metal air duct frame. I have no way of measuring the actual merv micro particle rating but I can say they filter dust about the same as other brands of filters I have used. I change our filters every two months. The price is excellent and I will purchase another case for next season.
