Made of high-quality aluminum oxide, which greatly improves the speed, power, service life, and durability. Multi-purpose disc that can be used for grinding, deburring, edge chamfering, blending & finishing. Used on cast iron, steel, stainless steel, aluminum, fiberglass, and plastic, as well as several other alloys. 7/8" Metal Reinforced Arbor Hole. MAX RPM: 13,300