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 1/4 in Inside Diameter 0.313 in Outside Diameter 47/64 in Maximum Thickness 0.065 in System of Measurement Inch Minimum Thickness 0.065 in Color Clear Inside Diameter Tolerance 0.307-0.327 Made in North America No Manufacturer Location Globally Sourced Material Quality Standards Not Rated Maximum Temperature 350 Degrees C