Lock Washer Lock Washer Type External Tooth Lock Finish Zinc Plated Material Steel For Screw Size 1/4 in Inside Diameter 0.267 in Outside Diameter 0.51 in Maximum Thickness 0.028 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 0.023 in to 0.028 in Package Quantity 100