5/16" x 0.688" OD Thru-Hardened Plain Finish Steel SAE General Purpose Flat Washer / PERIPHERAL SHAPE STYLE: 1 ROUND CENTER HOLE SHAPE STYLE: 1 ROUND CENTER HOLE WIDTH: 0.339 INCHES MINIMUM AND 0.359 INCHES MAXIMUM END ITEM IDENTIFICATION: MRAP - UNIQUE NSN - USED ON 4 MRAP VARIANTS PART NAME ASSIGNED BY CONTROLLING AGENCY: WASHER, .344 X .688 X .051 SPECIAL FEATURES: 5/16" PLAIN WASHER; .688 NOM OD; .344 NOM ID; .065 NOM THK MATERIAL: STEEL COMP 1010 OVERALL AND STEEL COMP 1020 SURFACE TREATMENT: ZINC OVERALL