Drill America Qualtech 29 piece 135 degrees split point heavy duty drill bit set comes in a metal case. Manufactured to National Aerospace Standard 907, these drills are ideal for portable or machine drilling of low tensile strength alloy materials. They have a black oxide surface treatment that is abrasion resistant, reduces chip welding and improves chip flow. These drills are self-centering and reduces thrust. 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 include fractional sizes: 1/16" to 1/2" (1/64 Increments).