SAE Washer Flat Washer Type SAE Dimensional Standards ASME B18.22.1 Type A Narrow SAE Standard Material Steel Material Grade/Class Grade 2 Finish Black Oxide For Screw Size 1/4 in Inside Diameter 0.281 in Outside Diameter 5/8 in Maximum Thickness 0.063 in System of Measurement Inch Minimum Thickness 0.063 in Pack Size Small Pack Rockwell Hardness 38HRC Thickness Tolerance +/-0.015 in Package Quantity 100