Polyester Blue Filters
(21.5 x 23 x 1) - 6 per box

These panel filters are rigidly constructed using a progressively dense fiberglass or Polystrand media to maximize dust holding capacity. The metal grids are thermally bonded to the internal sides of a heavy-duty one-piece craftboard frame. The Merv rating is 7 and suggest change within 30 to 90 days.