5/16" Mechanical Zinc Finish Medium Split Lock Washer / HOLE DIAMETER: 0.314 INCHES MINIMUM AND 0.322 INCHES MAXIMUM OUTSIDE DIAMETER: 0.583 INCHES NOMINAL END ITEM IDENTIFICATION: MRAP - COMMON NSN - USED ON 3 MRAP VARIANTS AND 1 OTHER WEAPON SYSTEM PART NAME ASSIGNED BY CONTROLLING AGENCY: WASHER,LOCK 5/16,REG,STL/ZNC MATERIAL: STEEL OVERALL SURFACE TREATMENT: ZINC OVERALL STYLE DESIGNATOR: 108 SPLIT HELICAL-RIGHT HAND