Five piece high-speed steel step drill: made of high-speed steel. Each drill bit has 6 or more sizes. It can replace 50 individual drill bits and handle holes with diameters up to 50. Quick and convenient to use: Although the diameters are different, the groove characteristics of the drill bit remain consistent. There is no need to remove the drill bit during the drilling process. Its titanium coating also helps reduce friction and heat generation, accelerating speed. Widely used: This tool can create holes and penetrate various types of materials, such as laminates, plastics, plywood, granular wood, acrylic acid, and thin metal sheets. You can also use it for different DIY and light homework projects. Aluminum storage box: Encapsulated in an aluminum shell, the drill bit is protected when not in use.