Made of high speed steel construction for proven capability and durability.<br> Twist design: increases cutting speed with self-centering and prevents walking, clears chips and particles faster<br> Suitable for all kinds of stainless steel, ordinary steel, angle iron, aluminum, copper, wood and other materials drilling.<br> For precise drilling, electronic assembling, tool making, model making, jewelry engraving, and hobbies.<br> Set includes: 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm<br> Specification:<br> Material: high speed steel<br> Size Chart:<br> Size: 21mm/0.83inch, 22mm/0.87inch, 23mm/0.91inch, 24mm/0.94inch, 25mm/0.98inch, 26mm/1.02inch, 27mm/1.06inch, 28mm/1.10inch<br> Package Includes:<br> 1 Piece Twist Drill Bit