USS Washer, Flat Washer Type USS, Dimensional Standards ASME B18.22.1, Material Steel, Material Grade/Class Grade 2, Finish Zinc Plated, For Screw Size 1/2 in, Inside Diameter 0.563 in, Outside Diameter 1 3/8 in, Maximum Thickness 0.109 in, System of Measurement Inch, Minimum Thickness 0.109 in, Pack Size Bulk Pack, Rockwell Hardness B49, Thickness Tolerance +/-0.010 in, Package Quantity 1300