5/16"-18 x 1" ASTM F835 Hex Drive Black Oxide Finish Alloy Steel Flat Socket Cap Screw / THREAD CLASS: 3A THREAD DIRECTION: RIGHT-HAND THREAD LENGTH: 0.772 INCHES MINIMUM AND 0.802 INCHES MAXIMUM FASTENER LENGTH: 0.970 INCHES MINIMUM AND 1.000 INCHES MAXIMUM HEAD STYLE: C50 FLAT COUNTERSUNK HEAD DIAMETER: 0.544 INCHES MINIMUM AND 0.600 INCHES MAXIMUM INTERNAL DRIVE STYLE: D5 HEXAGON END ITEM IDENTIFICATION: 2355-01-567-4930 TRUCK, BOMB SERVICE NOMINAL THREAD DIAMETER: 0.313 INCHES WIDTH ACROSS FLATS: 0.188 INCHES NOMINAL THREAD QUANTITY PER INCH: 18 HARDNESS RATING: 39.0 ROCKWELL C MINIMUM OVERALL AND 44.0 ROCKWELL C MAXIMUM PART NAME ASSIGNED BY CONTROLLING AGENCY: BLACK OXIDE FINISH FLAT SOCKET CAP SCREW COLOR: BLACK OVERALL MATERIAL: STEEL OVERALL MATERIAL DOCUMENT AND CLASSIFICATION: ASTM F835 ASSN STD SINGLE MATERIAL RESPONSE OVERALL SURFACE TREATMENT: BLACK CHEMICAL FINISH OVERALL THREAD SERIES DESIGNATOR: UNRC