Flat Washer Flat Washer Type Standard Dimensional Standards ANSI B18.22.1 Material PEEK Material Grade/Class Grade 2 Finish Plain For Screw Size 3/8 in Inside Diameter 0.096 in Outside Diameter 1/2 in Maximum Thickness 0.314 in System of Measurement Inch Minimum Thickness 0.314 in 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