Split Lock Washer Finish Black Oxide Material Steel For Screw Size 5/16 in Inside Diameter 0.314 in Outside Diameter 0.593 in Maximum Thickness 0.097 in Minimum Thickness 0.097 in Color Black Dimensional Standards ASME B18.21.1 Inside Diameter Tolerance +/-0.005 in Made in North America No Manufacturer Location Globally Sourced Material Grade/Class Not Graded Material Quality Standards ASTM A307A SAE J429 Maximum Temperature 275 Degrees F Minimum Temperature 10 Degrees F