... with low competitive strength and high drillability such as shale, clay, soft limestone, rock salt, gypsum,etcPayment termsL/C ... area.d. Being able to stand high RPM by using ball locked cone.e. Taking good advantage of ... entering into bearing lubrication system.g. Increasing the high temperature resistance of the seal & lube system by ... 3/8" Kingdream HA 447G TCI Tricone rock drill bit/three cone bit