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 3/8 in Inside Diameter 1.406 in Outside Diameter 2 19/32 in Maximum Thickness 0.313 in System of Measurement Inch Minimum Thickness 0.313 in Inside Diameter Tolerance 1.380 to 1.438 in Outside Diameter Tolerance 2.530 in to 2.600 in Pack Size Small Pack Rockwell Hardness 38HRC