Lock Washer Lock Washer Type External Tooth Lock Finish Zinc Plated Material Steel For Screw Size #4 Inside Diameter 0.123 in Outside Diameter 0.26 in Maximum Thickness 0.018 in Dimensional Standards ASME B18.21.1 For Use With Small Screws Material Grade/Class Not Graded Pack Size Small Pack Rockwell Hardness C40 to C50 System of Measurement Inch Package Quantity 100