Lock Washer Lock Washer Type Countersunk External Tooth Lock Finish Plain Material Stainless Steel For Screw Size #4 Inside Diameter 0.113 in Outside Diameter 0.213 in Maximum Thickness 0.015 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