Flat Washer Flat Washer Type Standard Dimensional Standards ANSI B18.22.1 Material PEEK Material Grade/Class Grade 2 Finish Plain For Screw Size M4 Inside Diameter 4.8 mm Outside Diameter 11.1 mm Maximum Thickness 1.1 mm System of Measurement Metric Minimum Thickness 1.1 mm Color Natural Maximum Temperature 500 Degrees F Minimum Temperature -50 Degrees F Pack Size Small Pack Resistance Properties Impact Resistant Radiation Resistant Wear Resistant Rockwell Hardness M103