This is a revolutionary new diamond tool that uses a unique brazing technology to bond a high concentration of high quality diamond to a steel surface. Use this for high and low carbon steel, stainless, concrete, hard faced alloys, stainless, welds, hard refractory, stone, plastic, fiberglass, composites, and ceramic. This cup will grind almost ANYTHING. The Diamond is constantly exposed resulting in FAST grinding action. So if you have a nasty hard application that you need to grind FAST, this is you product.