This is a KBC 1.15/16 Taper Shank HSS Expansion Chucking Reamer, It is straight flute. It is recommended for reaming abrasive materials and as the diameter wears down, the reamer can be expanded many times by tightening the end adjusting screw and regrinding to its original size. This is not for a larger size than specified. If you have any questions on this one, let us know. Our part number on this one is 1-131-160