Machined Countersunk Washer, Material Grade/Class Not Applicable, Material Steel, Finish Black Oxide, For Screw Size M6, Maximum Inside Diameter 6.4 mm, Outside Diameter 36 mm, Countersink Angle 90 Degrees , Overall Height 4 mm, System of Measurement Metric, Color Black, Dimensional Standards RoHS Compliant, For Use With Flat and Oval Head Screws, Industry Standards AMPG 2002 FIN.31, Minimum Inside Diameter 6.4 mm, Pack Size Small Pack, Rockwell Hardness C40, Thickness Tolerance +/-0.3 mm