Sq Washer for 5/8 Bolt .688 ID 2.00 Wd ., Dimensional Standards AMPG 2017 SQ.01, Material Steel, Material Grade/Class Case Hardened, Finish Zinc-Plated, For Screw Size 5/8 in, Inside Diameter 0.688 in, Outside Diameter Not Applicable, Maximum Thickness 9/32 in, System of Measurement Inch, Minimum Thickness 7/32 in, Made in North America Made in North America, Material Quality Standards ASTM A108