Flat Washer Flat Washer Type Standard Material Alloy Steel Material Grade/Class Grade 2 Finish Plain For Screw Size M20 Inside Diameter 22.32 mm Outside Diameter 39 mm Maximum Thickness 3.1 mm System of Measurement Metric Minimum Thickness 3.1 mm Color Blue Pack Size Small Pack Rockwell Hardness RC38 RoHS Compliant Yes Package Quantity 5