Square Washer, Dimensional Standards AMPG 2017 SQ.01, Material Steel, Material Grade/Class Case Hardened, Finish Black Oxide, For Screw Size 1 1/2 in, Inside Diameter 1.563 in, Outside Diameter Not Applicable, Maximum Thickness 17/64 in, System of Measurement Inch, Minimum Thickness 15/64 in, Color Black, Made in North America Made in North America, Material Quality Standards ASTM A108