The HP-XTRA Fasteners are used with PIRANHA XTRA Fastening Plates to secure mechanically fastened Sure-Weld roofing systems to steel decks. These Fasteners are #21 steel-threaded fasteners that feature deep buttress threads (13 threads per inch), a mini-drill point for enhanced back-out resistance, and an oversized truss head with a #3 Phillips drive. Enhanced Factory Mutual uplift approvals have been achieved due to the increased pullout valves associated with the HP-XTRA Fastener.