5/16"-18 x 2-3/4" ASTM F837 Hex Drive Grade 18-8 Stainless Steel Socket Cap Screw / THREAD CLASS: 3A FASTENER LENGTH: 2.750 INCHES NOMINAL HEAD STYLE: C1 HEXAGON NOMINAL THREAD DIAMETER: 0.312 INCHES THREAD QUANTITY PER INCH: 18 MATERIAL: STEEL CORROSION RESISTING OVERALL THREAD SERIES DESIGNATOR: UNC