Square Washer, Dimensional Standards AMPG 2017 SQ.01, Material Steel, Material Grade/Class Case Hardened, Finish Zinc-Plated, For Screw Size 1/2 in, Inside Diameter 0.563 in, Outside Diameter Not Applicable, Maximum Thickness 1/8 in, System of Measurement Inch, Minimum Thickness 7/64 in, Material Quality Standards ASTM A108, Pack Size Small Pack, Thickness Tolerance +/-0.031 in