Drill America Qualtech 13 piece 118 degrees conventional point general purpose drill bit set comes in a metal case. Features a left hand helix for screw machine applications where spindles rotate counterclockwise. Left hand drills can also be used to drill out broken bolts. 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. Round shanks allow use with a wide variety of toolholding systems. Reverse-flute drill bits run in the opposite (clockwise) direction from regular drill bits when making holes. Set include fractional sizes: 1/16" to 1/4" (1/64 Increments).