... & good service 4. Good feedback of clients 17 1/2" tricone drill bit : size from ... 1/2",9 5/8",9 7/8",12 1/4",17 1/2", etc. IADC Code: ... Type AvailableSize: 5 7/8",6",6 1/2",7 1/2",7 7/8",8 1/2 ... ",9 1/2",9 5/8",9 7/8",12 1/4",14 3/4",17 ... etc. IADC Code:5-- Series,6-- Series,7-- 4,Non-Sealed Roller Bearing BitCutting StructureThe durability ... 9 5/8",9 7/8",12 1/4",15",15 1/2",17 1/2", etc ...