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