Lock Washer, Carbon Steel, Carbon Steel, Finish Zinc Plated, Fits Bolt Sizes 20mm, M20, Inside Dia. 20.7 mm, Outside Dia. 30.7 mm, Thickness 6.01 mm, Thickness Tolerance +/- 0.32 mm, Color Gray, Rockwell Hardness C46, Helps Prevent Loosening, For Use With Bolts, Package Quantity 100. This item has been restricted from sale in the following state (s): []