Spherical Washer Bottom Washer Inside Diameter 12 mm Bottom Washer Outside Diameter 21 mm Bottom Washer Radius 15 mm Finish Plain For Screw Size M10 Material Stainless Steel Material Grade/Class 18-8 Maximum Thickness 6.5 mm Minimum Thickness 6.5 mm Pack Size Small Pack Rockwell Hardness B83 to B95 Spherical Washer Type Spherical Washer Assembly System of Measurement Metric Top Washer Inside Diameter 10.5 mm Top Washer Outside Diameter 21 mm 1 Pair