USS Washer Flat Washer Type USS Dimensional Standards ASME B18.22.1 Material Steel Material Grade/Class Grade 8 Finish Zinc Yellow For Screw Size 1/4 in Inside Diameter 0.313 in Outside Diameter 3/4 in Maximum Thickness 0.136 in System of Measurement Inch Minimum Thickness 0.192 in Color Yellow Material Quality Standards ASTM F436 Pack Size Small Pack Rockwell Hardness RC38 Package Quantity 100