Sizes included are 9/16, 5/8, 3/4, 7/8 and 1 with 1/2 reduced shanks; 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; When run in a counterclockwise direction (right-clockwise direction. Hand cut) spiral Fluted tools evacuate chips up and out of the cut to reduce clogging; Ideal for drilling in low and medium tensile strength materials