United Abrasives vitrified grinding mounted points are made from aluminum oxide grain. Use for deburring and finishing ferrous metals such as iron, steel and welds. These mounted points are a low cost alternative to carbide burs and is dressed for perfect balance to perform without vibration or run-out. Fast stock removal. Type "A" is designed for offhand applications, Type "B" is designed for light deburring applications and Type "W" is designed for medium to heavy stock removal.