Mil. Spec. Flat Washer, Flat Washer Type Mil-Spec, Dimensional Standards MS15795, Material Stainless Steel, Material Grade/Class 18-8, Finish Plain, For Screw Size 5/16 in, Inside Diameter 0.344 in, Outside Diameter 11/16 in, Maximum Thickness 5/64 in, System of Measurement Inch, Minimum Thickness 3/64 in, Inside Diameter Tolerance +/-0.010 in, Material Quality Standards ASTM A380, ASTM A582, Outside Diameter Tolerance +/-0.010 in, Pack Size Small Pack