PFERD vitrified bond mounted point is made of grey silicon Carbide in a vitrified bond. These product is noted for their hardness and durability. Hardness grade R mounted points are ideally suited for heavy-duty edge grinding on castings. It is distinguished by their high edge-holding capability, long service life and low wear. Due to their special edge-holding properties, hardness grade R mounted points can also be used economically with low RPM power tools. Removal of sharp burrs on castings (grey and nodular cast iron). removal of sand inclusions and scale from castings. In edge grinding operations, hardness grade R mounted points perform best at a recommended peripheral speed of 6, 000 - 9, 800 SFPM. For surface grinding we recommend a peripheral speed of 4, 000 - 6, 000 SFPM. Suitable drive systems include flexible shafts and electric or air-powered straight grinders. Specification: shape/form: W222; diameter (inches): 1; Length (inches): 2; shank diameter (inches): 1/4; shank Length (inches): 1-1/2; Grit: 30; maximum rotational speed (RPM): 15900; material: silicon Carbide.