Jumbo Washer Flat Washer Type Oversized Dimensional Standards AMPG 2001 FL.05 Material Steel Material Grade/Class Grade 2 Finish Black Oxide For Screw Size 4 in Inside Diameter 4.125 in Outside Diameter 7 1/2 in Maximum Thickness 0.312 in System of Measurement Inch Minimum Thickness 0.312 in Color Black Inside Diameter Tolerance +/-0.010 in Material Quality Standards ASTM A108 Outside Diameter Tolerance +/-0.010 in Pack Size Small Pack Rockwell Hardness C40