... service 4. Good feedback of clients 17 1/2" tricone drill bit : size from 60mm to 26 inch,metal sealed and ... 7/8",12 1/4",17 1/2", etc. IADC Code:4-- Series, 5-- Series, 6-- Series,etc. 2. Elastomer sealed ... 1/4",14 3/4",17 1/2", etc. IADC Code:4-- Series, 5-- Series, 6-- Series,etc. 3. Air Cooling ... 7/8",10 5/8",12 1/4", etc. IADC Code:5-- Series,6-- Series,7-- 4,Non-Sealed Roller Bearing ...