Drill America Qualtech 115 piece drill blank set comes in a metal case. Hardened and ground, blanks are often used as gages to check hole size and drill bushing size. Can often be used as guide pins for die sets or modified as punches. 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. When run in a counterclockwise direction (right-hand cut) spiral fluted tools evacuate chips up and out of the cut to reduce clogging. Set includes combination of fraction, letter, and wire sizes: 1/16" to 1/2" (1/64 Increments); A to Z; # 1 to # 60.