Lock Washer Lock Washer Type Internal and External Tooth Lock Finish Zinc Plated Material Steel For Screw Size 3/8 in Inside Diameter 0.384 in Outside Diameter 1.13 in Maximum Thickness 0.042 in Dimensional Standards ASME B18.21.1 Material Grade/Class Not Graded Pack Size Small Pack Rockwell Hardness C40 to C50 System of Measurement Inch Package Quantity 50