USS Washer Flat Washer Type USS Dimensional Standards ASME B18.21.1 Material Steel Material Grade/Class Grade 2 Finish Black Oxide For Screw Size 5/16 in Inside Diameter 0.375 in Outside Diameter 7/8 in Maximum Thickness 0.083 in System of Measurement Inch Minimum Thickness 0.083 in Color Clear Inside Diameter Tolerance 0.37-0.39 Made in North America No Manufacturer Location Globally Sourced Material Quality Standards Not Rated Maximum Temperature 350 Degrees C