... service 4. Good feedback of clients 17 1/2" tricone drill bit : size from 60mm to 26 inch ... new formulas and new techniques for insert bit. Gauge StructureMultiple gauge protection with gauge trimmers ... Available Size: 6",6 1/2",7 1/2",8 1/2",9 1/2",9 5/8", ... with new formulas and new techniques for insert bit. Bearing StructureNon-sealed roller bearing. Drilling ... 3/4",6",6 1/2",7 1/2",8 1/2",9 1/2",9 5/8 ...