Flat Washer Flat Washer Type Standard Dimensional Standards DIN 125-1A Material Steel Material Grade/Class Grade 2 Finish Zinc Plated For Screw Size M30 Inside Diameter 31 mm Outside Diameter 56 mm Maximum Thickness 4 mm System of Measurement Metric Minimum Thickness 4 mm Color Silver Inside Diameter Tolerance 1.22-1.236 Made in North America No Manufacturer Location Globally Sourced Material Quality Standards Not Rated Maximum Temperature 350 Degrees C