Flat Washer, Dimensional Standards AMPG 2001 FL.01, Material Steel, Material Grade/Class Case Hardened, Finish Black Oxide, For Screw Size 1/2 in, Inside Diameter 0.531 in, Outside Diameter 1 1/2 in, Maximum Thickness 7/32 in, System of Measurement Inch, Minimum Thickness 7/32 in, Color Black, Made in North America Made in North America, Material Quality Standards ASTM A108, Thickness Tolerance +0.005/-0.020 in