... : 6",6 1/2",7 1/2",8 1/2",9 1/2",9 5/8",9 7/8",12 1/4",17 1/2", etc. IADC ... ",9 5/8",9 7/8",12 1/4",14 3/4",17 1/2", etc. IADC Code:4-- Series, 5-- Series, 6 ... ",9 5/8",9 7/8",10 5/8",12 1/4", etc. IADC Code:5-- Series,6-- Series,7-- 4, ... 1/2",7 1/2",8 1/2",9 1/2",9 5/8",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 ...