... 4",17 1/2", etc. IADC Code:4-- Series, 5-- Series, 6-- Series,etc. 2. Elastomer sealed bearing Tricone BitCutting StructureThe ... 4",17 1/2", etc. IADC Code:4-- Series, 5-- Series, 6-- Series,etc. 3. Air Cooling Roller Bearing Tricone BitCutting ... /2",9 5/8",9 7/8",10 5/8",12 1/4", etc. IADC Code:5-- Series,6-- Series,7-- 4 ... /2",17 1/2", etc. IADC Code:5-- Series,6-- Series 17 1/2" tricone drill bit