Sq Washer for 5/8 Bolt .688 ID 4.00 Wd 1, Dimensional Standards AMPG 2017 SQ.01, Material Stainless Steel, Material Grade/Class Case Hardened, Finish Black Oxide, For Screw Size 5/8 in, Inside Diameter 0.688 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