Flat Washer Flat Washer Type Standard Dimensional Standards ANSI B18.22.1 Material Stainless Steel Material Grade/Class 18-8 Finish NL-19 For Screw Size 5/16 in Inside Diameter 0.344 in Outside Diameter 3/4 in Maximum Thickness 0.05 in System of Measurement Inch Minimum Thickness 0.05 in Color Silver Pack Size Small Pack Resistance Properties Corrosion Resistant Rockwell Hardness B70 Thickness Tolerance +/-0.005 in Package Quantity 50