5/16"-18 x 1-1/2" ASTM A574 Hex Drive Black Oxide Finish Alloy Steel Socket Cap Screw / THREAD CLASS: 3A THREAD DIRECTION: RIGHT-HAND THREAD LENGTH: 1.120 INCHES NOMINAL FASTENER LENGTH: 1.460 INCHES MINIMUM AND 1.500 INCHES MAXIMUM HEAD STYLE: C1 HEXAGON HEAD HEIGHT: 0.306 INCHES MINIMUM AND 0.312 INCHES MAXIMUM WIDTH BETWEEN FLATS: 0.457 INCHES MINIMUM AND 0.469 INCHES MAXIMUM NOMINAL THREAD DIAMETER: 0.312 INCHES THREAD QUANTITY PER INCH: 18 PART NAME ASSIGNED BY CONTROLLING AGENCY: SCR,CAP SOC .31-18X1.50 BO MATERIAL: STEEL OVERALL MATERIAL DOCUMENT AND CLASSIFICATION: ASTM A574 ASSN STD ALL MATERIAL RESPONSES OVERALL SURFACE TREATMENT: BLACK CHEMICAL FINISH OVERALL THREAD SERIES DESIGNATOR: UNC