Description: Made of high speed steel construction for proven capability and durability. Twist design: increases cutting speed with self-centering and prevents walking, clears chips and particles faster. Portable and compact size to be stored easily in pocket or tool box. Suitable for all kinds of stainless steel, ordinary steel, angle iron, aluminum, copper, wood and other materials drilling. For precise drilling, electronic assembling, tool making, model making, jewelry engraving, and hobbies. Specification: Material: High Speed Steel Size: 15mm; 15.5mm; 17mm; 17.5mm; 16.5mm Package Includes: 1 Piece Twist Drill Bit