Flat Washer, Flat Washer Type Standard, Dimensional Standards AMPG 2001 FL.06, Material Alloy Steel, Material Grade/Class Through Hardened, Finish Zinc Yellow, For Screw Size 1/4 in, Inside Diameter 0.281 in, Outside Diameter 5/8 in, Maximum Thickness 7/64 in, System of Measurement Inch, Minimum Thickness 3/32 in, Color Yellow, Inside Diameter Tolerance +/-0.010 in, Made in North America Made in North America, Material Quality Standards ASTM A108, Outside Diameter Tolerance +/-0.010 in