Flat Washer Flat Washer Type Oversized Dimensional Standards AMPG 2003 FIT-TIGHT.01 Material Steel Material Grade/Class Grade 2 Finish Black Oxide For Screw Size 1/2 in Inside Diameter 0.531 in Outside Diameter 1 3/8 in Maximum Thickness 0.166 in System of Measurement Inch Minimum Thickness 0.146 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/-0.020 in