... 4. Good feedback of clients 17 1/2" tricone drill bit : size from 60mm to 26 inch,metal sealed ... seal.Main Type Available Size: 6",6 1/2",7 1/2",8 1/2",9 1/2",9 ... performance.Main Type AvailableSize: 5 7/8",6",6 1/2",7 1/2",7 7/8",8 1/2",9 1 ... 4", etc. IADC Code:5-- Series,6-- Series,7-- 4,Non-Sealed Roller Bearing BitCutting StructureThe durability of premium ... : 2 3/8",3",3 5/8:",3 7/8",4",4 1/2",4 5/8",4 ...