Split Lock Washer, Lock Washer Type Split Lock, Finish Black Oxide, Material Steel, For Screw Size 5/16 in, Inside Diameter 0.322 in, Outside Diameter 0.583 in, Maximum Thickness 0.078 in, Minimum Thickness 0.078 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