Features 1、M35 Grade Cobalt Steel: Made of strong M35 grade cobalt steel, with 5% cobalt added to form a hardened heat resistant alloy with longer life 2、9 Size Ranges: With 9 size ranges from 4mm to 12mm, you can use one drill bit to drill up to 9 holes of different diameters, saving your time and effort to replace the drill bit 3、Application: Very suitable for drilling new holes or expanding existing holes on stainless steel, and softer metals such as iron, brass, copper, aluminum, etc. 4、Greater Torsion: This 1/4in hex shank drill bit can be clamped tighter by compatible drill bits and screwdrivers to achieve greater torsion 5、Smooth Chip Removal: This is a M35 cobalt containing step drill, which can open holes quickly, cut faster, and remove chips smoothly. Specification Item Type: Spiral Step Drill Bit Material: High Speed Steel Containing Cobalt Purpose: Spiral Step Drill Shank Type: Hex Shank Shank Diameter: 1/4in Drilling Diameter: Approx. 4-12mm / 0.16-0.47in Package List 1 x Spiral Step Drill Bit