Feature 1Unique 3 Sided Shank: Compared with traditional drills, spiral step drills are nearly impossible to buckle. The unique 3 sided shank prevents slipping into the drill chuck and reduces impact, which is recommended to lubricate the drill before each use to extend service life. 2Design Optimization: The spiral step drill bit slot design and the 3 side shank design are optimized for high speed cordless drilling rigs, providing greater speed and control, while minimizing the flying of steel plates, thereby prolonging the service life. 310 Size Drill Bits: The spiral step drill bit has 10 sizes, so you can drill 10 holes according to different diameters, which saves you the time and effort to replace the drill bit. 4Drilling Depth: The drilling depth can be as high as 0.07in (about 0.2 cm) of steel plate, acrylic, PVC, and wooden boards within 0.2in (about 0.5 cm). 5Robust High Speed Steel Structure: The spiral step drill bit with strong high speed steel structure is adopted to improve durability. The new spiral slot design cuts faster and straighter, and can automatically deburr when you drill. Item Type: Spiral Step Drill BitMaterial: High Speed SteelPurpose: Spiral Step Drill BitColour: Dark YellowTool Handle Size: 3/8inDrilling Range: 1/4in-1-3/8inStep Size: 1/4in, 3/8in, 1/2in, 5/8in, 3/4in, 7/8in, 1in, 1-1/8in, 1-1/4in, 1-3/8inScope of Application: Use with Pistol Drill or Electric Drill Package List 1 x Spiral Stepped Drill BitNotePlease do not set the drilling speed to the maximum value to avoid damaging the cutting edge.