The DUO-PAK 40 is designed for applications where long service life with a dual pocket medium efficiency filter is required. The DUO-PAK 40, 1 ply configuration, which utilizes a tackified single density polyester media, offers an economical alternative for applications where high dust holding capacity in a primary filter is required. The self-sealing feature of the DUO-PAK 40 prevents air bypass and eliminates the need for clips; saving time and money during change-outs. The long service life and low cost make the DUO-PAK 40 an ideal replacement for four-inch, or six-inch pleat applications where holding frames, or flat bank side access housings are in use. Models with headers are available at an additional charge.