Machined Countersunk Washer, Material Grade/Class Not Applicable, Material Steel, Finish Black Oxide, For Screw Size 1/4 in, Maximum Inside Diameter 0.281 in, Outside Diameter 2 in, Countersink Angle 82 Degrees , Overall Height 0.281 in, System of Measurement Inch, Color Black, Dimensional Standards RoHS Compliant, For Use With Flat and Oval Head Screws, Industry Standards AMPG 2002 FIN.31, Minimum Inside Diameter 0.281 in, Pack Size Small Pack, Rockwell Hardness C40