1/2"-13 x 4" Phosphate and Oil Finish SAE J429 Grade 8 Hex Flange Bolt / FASTENER LENGTH: 4.00 INCHES NOMINAL HEAD DIAMETER: 0.25 INCHES NOMINAL THREAD QUANTITY PER INCH: 13.0 PART NAME ASSIGNED BY CONTROLLING AGENCY: HEX FLANGE BOLT BEARING SURFACE OF HEAD SURFACE TREATMENT: BLACK CHEMICAL FINISH SPECIAL FEATURES: UNSERRATED;BLACK PHOSPHATE & OIL NONDEFINITIVE SPEC/STD DATA: 8 GRADE