Contents: 1 set (3pcs) of step drill bits with nylon bag Features: Color: Gold. < p >Surface: Titanium. Material: High Speed Steel. Step drill bit cutting size: 4-12mm (4/6 /8 /10 /12mm). 4-20mm (4/6/8/10/12/14/16/18/20mm). 4- 32mm (4 /6/8/10/12/14/16/18/20/22/24/26/28/30/32mm). HSS and Titanium Coated, our step drill bits are made of super strong HSS steel and coated with titanium to make them even more durable. A variety of drill bit diameters, reaming, chamfering, deburring and drilling. A ladder drill can meet your different needs. Widely used to drill holes in a variety of materials such as steel, wood, thin iron and aluminum alloys. Note: 1. During the operation, it is necessary to inject water to cool the drill bit. In the case of operation, high temperature smoke is easy to bake, to avoid reducing the life of the tip. 2. Suitable for workpieces with a hardness of 25° or less and a thickness of less than 5 mm for wood, plastic and thin metal. It is recommended that the speed of