5/16"-18 Grade 2 Zinc Finish NE Steel Nylon Insert Lock Nut / THREAD CLASS: 2B THREAD DIRECTION: RIGHT-HAND LOCKING FEATURE: PREVAILING TORQUE WITH NONMETALLIC INSERT NUT STYLE: A12 HEXAGON NUT HEIGHT: 0.250 INCHES NOMINAL END ITEM IDENTIFICATION: 4320-01-617-7587 WIDTH ACROSS FLATS: 0.489 INCHES MINIMUM AND 0.502 INCHES MAXIMUM THREAD SERIES: UNC THREAD QUANTITY PER INCH: 18 NOMINAL THREAD SIZE: 0.312 INCHES BEARING SURFACE TYPE: FLAT PART NAME ASSIGNED BY CONTROLLING AGENCY: HEX NYLON INSERT LOCKNUTS (NM AND NE) MATERIAL: STEEL OVERALL MATERIAL: PLASTIC NYLON LOCKING INSERT SURFACE TREATMENT: ZINC OVERALL