Drill BitChina 7 1/2inch190.5mm Milled Tooth IADC117/127/227/315tricone Bit/Rock Bit/Drilling Bit, Find details about China Steel Tooth Bit Tricone Rock Drilling from 7 1/2inch190.5mm Milled Tooth IADC117/127/227/315tricone Bit/Rock Bit/Drilling Bit