Dupont flex wrap Nf is a premium performance, extendable self-adhered flashing material that can be applied over a wide range of building substrates, including non-nail able sheathing materials like PS foam board, Fiberboard, concrete masonry unit (cmu), and other such materials. Dupont flex wrap Nf does not require the use of mechanical fasteners in the flexed corner areas when installed according to the flashing installation guidelines issued by DuPont. Available in 6" x 75' and 9" X 75'.