... and increases ROP. 5. Product Application It is suitable for sidetracking, deep well drilling and old well repairing. Size Bit TypeIn.mm4 ... 537, 6175 7/8149.2517, 527, 537, 6176152.4517 used for: geoloical prospecting,development of oil and gas,drilling water wells ... ,blast holes and making holes for seismic prospecting,construction engineering.now there are eleven common ...