Flat Washer Flat Washer Type Standard Dimensional Standards ASME B18.22.1 Material Stainless Steel Material Grade/Class 316 Finish NL-19 For Screw Size 5/16 in Inside Diameter 0.344 in Outside Diameter 11/16 in Maximum Thickness 0.177 in System of Measurement Inch Minimum Thickness 0.122 in Color Silver Pack Size Small Pack Resistance Properties Corrosion Resistant Rockwell Hardness B70 Thickness Tolerance +0.051 to 0.080 in Package Quantity 10