Lock Washer Lock Washer Type Internal Tooth Lock Finish Plain Material Phosphor Bronze For Screw Size 3/8 in Inside Diameter 0.398 in Outside Diameter 0.692 in Maximum Thickness 0.04 in Color Bronze 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 B90 System of Measurement Inch Thickness Tolerance 0.032 in to 0.04 in Package Quantity 50