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 1/4 in Inside Diameter 0.281 in Outside Diameter 3/4 in Maximum Thickness 0.15 in System of Measurement Inch Minimum Thickness 0.13 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