Advance Sintered Tech diamond bits have diamonds directly embedded in the steel tip. As the metal tip wears off, new diamonds come to the surface. The life of any type of diamond stone bit depends upon the hardness, abrasiveness, and thickness of the material being drilled and other factors ( drill speed, pressure, and lubrication).
Coolman stone bit offers a wide range of diameter: 6mm – 105mm.
Please do take note that “drilling” with a stone bit is not as fast as drilling with the whole saw, it consumes slightly more time. The concept of the stone bit is not “drilling”, but “grinding” a hole. Water is required in the process of “ drilling with a stone bit.