Square Washer, Dimensional Standards AMPG 2017 SQ.01, Material Steel, Material Grade/Class Case Hardened, Finish Black Oxide, For Screw Size 3/8 in, Inside Diameter 0.438 in, Outside Diameter Not Applicable, Maximum Thickness 1/8 in, System of Measurement Inch, Minimum Thickness 7/64 in, Color Black, Material Quality Standards ASTM A108, Pack Size Small Pack, Resistance Properties Corrosion-Resistant, Thickness Tolerance +/-0.031 in