Michigan Drill high speed steel reduced shank aligning reamers are used to align existing holes prior to rivet or bolt installation. The point is tapered to allow entry into overlapping holes. They are also useful in portable reaming. Fits 1/2-inches chucks. High-speed steel tools are good for most general purpose applications, offering a combination of hardness and toughness for wear resistance. Black oxide treatment adds lubricity and creates small pockets on the surface of the tool that act to hold coolant near the cutting edge. These round shank tools have flats ground onto three sides to reduce slippage of the bit when used in drill chucks. Reverse (left hand) spiral flute tools push chips forward into the cut as they work, so they won't pull thin material towards the tool as it cuts and are useful for interrupted cuts such as keyways. Right-hand cut tools have a cutting action that engages when they are run in a clockwise direction.