Thick Washer Flat Washer Type Standard Material Steel Material Grade/Class Grade 5 Finish Black Oxide For Screw Size 5/16 in Inside Diameter 0.344 in Outside Diameter 3/4 in Maximum Thickness 0.125 in System of Measurement Inch Minimum Thickness 0.125 in Color Black Inside Diameter Tolerance +/-0.010 in Outside Diameter Tolerance +/-0.010 in Pack Size Small Pack Rockwell Hardness C4 Thickness Tolerance +0.005/-0.004 in Package Quantity 25