Steel balls of this type are usually made of stainless steel and is used inter alia in anti-friction bearings. This ball with diameter 50mm rather in something larger camps, about the turntables of excavators. I had ordered for pendulum tests and the package came in a short time with me. The ball itself was found loose in cardboard scraps and after I cleaned it I noticed some rust on the surface. This can occur, for example, when the ball is stored in humid air without sufficient oil. Most of the rust I could polish away now, they would have but can easily be avoided, so a point deduction. The second point would be the price, I know now at least another trader where such a steel ball in better quality will cost about half. And another quality: This and some other interesting data are not even listed in this article ...
