Lock Washer Lock Washer Type External Tooth Lock Finish Zinc Plated Material Steel For Screw Size 3/8 in Inside Diameter 0.398 in Outside Diameter 0.694 in Maximum Thickness 0.04 in Dimensional Standards ASME B18.21.1 For Use With Large Round Pan or Binding Head Screws Material Grade/Class Not Graded Pack Size Small Pack Rockwell Hardness C38 to C46 System of Measurement Inch Thickness Tolerance 0.032 in to 0.040 in Package Quantity 100