... Quality products & good service 4. Good feedback of clients 17 1/2" tricone drill bit : size from 60mm to ... and durability of bearing seal.Main Type Available Size: 6",6 1/2",7 1/2",8 1/2",9 ... the seal performance.Main Type AvailableSize: 5 7/8",6",6 1/2",7 1/2",7 7/8",8 ... 4 1/2",4 5/8",4 3/4",6",6 1/2",7 1/2",8 1/2",9 ... 1/4",15",15 1/2",17 1/2", etc. IADC Code:5-- Series,6-- Series 17 1/2" tricone drill bit ...