Hardened Steel Washer Flat Washer Type Standard Material Steel Material Grade/Class Grade 8 Finish Black Oxide For Screw Size 1/2 in Inside Diameter 0.5 in Outside Diameter 1 1/16 in Maximum Thickness 0.136 in System of Measurement Inch Minimum Thickness 0.177 in Material Quality Standards ASTM F436 Pack Size Small Pack Package Quantity 25