... 5/8",9 7/8",12 1/4",17 1/2", etc. IADC Code:4-- Series, 5-- Series, 6-- Series,etc. 2. Elastomer sealed bearing ... ",9 7/8",12 1/4",14 3/4",17 1/2", etc. IADC Code:4-- Series, 5-- Series, 6-- Series,etc. 3. Air Cooling ... ",9 7/8",12 1/4",15",15 1/2",17 1/2", etc. IADC Code:5-- Series,6-- Series 17 1/2" tricone drill bit ...