... Bits1)The 415 tci bits are used to drill low compressive strength, very soft formations.2)TCI bits maximize the use of ... Available Size: 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 Code:4 ... :",3 7/8",4",4 1/2",4 5/8",4 3/4",6",6 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 ...