Titanium Coating HSS - ROGAPER high-speed steel drill bits, fortified with a titanium coating that makes the drill bit harder than a typical HSS bit, can reduce the friction drill, and perform well in heat, corrosion, and rust resistance. Spiral Grooved Design - The tip bifurcates at 118 degrees for added wear resistance. The two-groove design provides a smoother cut, allowing material particles to escape easily for a cleaner drilling operation. Excellent Applicability - Ideal for plastic/wood/board/soft rubber with low hardness countersinks. Suitable for home DIY and general construction/engineering use. 1/4" Hex Shank - Caters to most pistols on the market to prevent slipping and falling off during rotation to increase safety in use. 31 Step Sizes - 13 step drill (1/8, 5/32, 3/16, 7/32, 1/4, 9/32, 5/16, 11/32, 3/8, 13/32, 7/16, 15/32, 1/2-inch) 6 step drill (3/16, 1/4, 5/16, 3/8, 7/16, 1/2-inch) and 12 step drill (3/16, 1/4, 5/16, 3/8, 7/16, 1/2, 9/16, 5/8, 11/16, 3/4, 13/16, 7/8-inch). With the step drill bits we offer, you can machine holes of different diameters.