The NaturalAire Standard has an ASHRAE 52.2 rating of MERV 8. Standard pleated furnace filters. Made of a 1 sided metal reinforced pleated media, recyclable, clay coated moisture resistant frame. Captures particles as small as 1 microns and is effective against the following contaminants, pet dander, mold spores, dust mite, debris pollen, household dust debris and lint