1.For enlarging,polishing and deepening existing holes on natural stone, artificial stone and concrete.
2.Diamond grains are firmly vacuum brazed onto the steel body,which provides higher efficiency and longer life,several times better than electroplated ones.
3.You can expect each bit to last dozens of holes processing marble and similar stones. 
4.Use wet or dry. But water or other coolant is recommended for longer life of the bit.

5.Various grit sizes and specification are available upon request.