This set includes four different sizes of tools, ranging from 0 to 4.8mm. The sizes included in the set are 0 - 0.8mm, 0.8 - 1.3mm, 1.3 - 3.1mm, and 3.1 - 4.8mm. These tools may be used for a variety of purposes, such as drilling, grinding, cutting, or polishing. The specific use and application of these tools will depend on their size and the material they are intended to work on. Whether you are a professional tradesperson or a DIY enthusiast, this set of tools is a useful addition to your toolkit.