5/16"-18 x 1-1/4" ASTM F879 Hex Drive 18-8 Stainless Steel Button Socket Cap Screw / THREAD CLASS: 2A THREAD DIRECTION: RIGHT-HAND THREAD LENGTH: 1.250 INCHES NOMINAL FASTENER LENGTH: 1.250 INCHES NOMINAL HEAD STYLE: C30 BUTTON HEAD DIAMETER: 0.527 INCHES MINIMUM AND 0.547 INCHES MAXIMUM HEAD HEIGHT: 0.152 INCHES MINIMUM AND 0.166 INCHES MAXIMUM INTERNAL DRIVE STYLE: D5 HEXAGON NOMINAL THREAD DIAMETER: 0.312 INCHES WIDTH ACROSS FLATS: 0.312 INCHES NOMINAL THREAD QUANTITY PER INCH: 18 MATERIAL: STEEL CORROSION RESISTING OVERALL THREAD SERIES DESIGNATOR: UNC