5/16"-18 Grade C ECOGUARD® Finish Steel Top Lock Nut / THREAD CLASS: 3B THREAD DIRECTION: RIGHT-HAND LOCKING FEATURE: PREVAILING TORQUE ALL METAL DESIGN NUT STYLE: A12 HEXAGON END ITEM IDENTIFICATION: 2330-01-603-3559,SEMITRAILER,LOW BED WIDTH ACROSS FLATS: 0.511 INCHES NOMINAL THREAD SERIES: UN NOMINAL THREAD SIZE: 0.312 INCHES BEARING SURFACE TYPE: CHAMFERED PART NAME ASSIGNED BY CONTROLLING AGENCY: NUT,HEX,PERVAILING TORQUE MATERIAL: STEEL OVERALL SURFACE TREATMENT: ZINC OVERALL