can drill a broad range of geological formations from the softest to the hardest rock. The surface set diamond core bits ... step crown design provides good stability. The discharged diamond core bits, of large water and big size stone, are ... diamonds are sharper ensuring faster cutting while still increasing bit life.Size Available:Q Series: AQ,BQ,NQ,HQ ... Series: EWG,AWG,BWG,NWG,HWG surface set core bit