4" Furnace Filter 4" Furnace Filter

4" replacement furnace filters are available in many standard and non-standard sizes. Simply select your size from the drop down box below to choose your filter size. Keep in mind that length and width are reversible (i.e. a 15x20x4 is the same as a 20x15x4).

4" replacement furnace filters are available in many standard and non-standard sizes. Simply select your size from the drop down box below to choose your filter size. Keep in mind that length and width are reversible (i.e. a 15x20x4 is the same as a 20x15x4).