... inserts on the heel rows and inner rows. 2)This design provides a fast drilling rate and added cutting structure durability ... Type Available Size: 6",6 1/2",7 1/2",8 1/2",9 1/2",9 5/8",9 7/8",12 ... dropping to minimum.Main Type AvailableSize: 8 1/2",9 1/2",9 5/8",9 7/8",10 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:5-- Series,6-- Series ...