Sealing Washer Finish Plain Metal Material Copper Material Grade/Class Not Graded For Screw Size M21 Inside Diameter 21 mm Outside Diameter 26 mm Maximum Thickness 1.5 mm Seal Material Copper System of Measurement Metric Pack Size Small Pack Heat Treatment Annealed Minimum Thickness 1.5 mm Thickness Tolerance +/-0.20 mm Package Quantity 25