USS Washer Flat Washer Type USS Dimensional Standards ASME B18.22.1 Type A Wide USS Standard Material Steel Material Grade/Class Grade 2 Finish Black Oxide For Screw Size 2 1/2 in Inside Diameter 2.625 in Outside Diameter 5 in Maximum Thickness 0.281 in System of Measurement Inch Minimum Thickness 0.21 in Pack Size Small Pack Resistance Properties Corrosion Resistant Rockwell Hardness 38HRC Thickness Tolerance +/-0.035 in Package Quantity 10