The Parafast® HD Fastener is a heavy duty roofing screw which is precoated with CR-10 corrosion resistant coating. The Parafast® HD Fastener, in conjunction with the Parafast® 3-inch metal plate, is designed to secure roof insulation and substrate panels, and base sheets in approved assemblies, to heavy steel decks. The Parafast® HD Fastener can also be used as an alternative to the Parafast® CD-10 Fastener in applications over structural concrete roof decks.