Made of wear-resistant tungsten carbide. For drilling glass, semiprecious stones, porcelain, ceramics, marble and other hard stones. The hard stones are subdivided according to the degree of hardness from 1 - 10. Tungsten carbide can be used up to hardness degree 6. Drilling hard stones with a hardness degree of more than 6 calls for the use of diamond tools. Shaft Ø 3.0mm. With ideal cutting angle of 6°.