SAE Washer Flat Washer Type SAE Dimensional Standards ASME B18.22.1 Material Steel Material Grade/Class Grade 8 Finish Zinc Yellow For Screw Size 5/16 in Inside Diameter 0.344 in Outside Diameter 11/64 in Maximum Thickness 0.051 in System of Measurement Inch Minimum Thickness 0.08 in Color Yellow Material Quality Standards ASTM F436 Pack Size Bulk Pack Rockwell Hardness C38 Package Quantity 8300