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 Thickness Tolerance 0.086 to 0.132 in Package Quantity 1300