Lock Washer Lock Washer Type Countersunk External Tooth Lock Finish Plain Material Stainless Steel For Screw Size 3/8 in Inside Diameter 0.383 in Outside Diameter 0.765 in Maximum Thickness 0.028 in Dimensional Standards ASME B18.21.1 Material Grade/Class 18-8 Pack Size Small Pack Rockwell Hardness C40 to C50 System of Measurement Inch Package Quantity 50