Excellent Performance - Drill bits have a unique hollow design for clean drilling and fast chip removal. They can help you open a perfect hole without burrs and wobbles. The tool has small incision resistance and fast punching speed, which improves work efficiency and saves time and effort. Economical set - This set of tools drill bit contains a total of 7 diamond hole saws. Length: 5cm. Diameter: 10, 25, 40, 55, 70, 80, 100mm. Different sized tools are available to meet your different drilling needs. They are ideal for processing materials such as glass. How to use them: They only need to be fitted to a normal power drill to work. As you work you should add cooling water to your surfaces, starting at a 45 degree angle then drilling vertically. Your force should be gentle, especially when drilling is started and drilling is complete. Multiple Uses: Opening tools are ideal for fragile hard materials such as glass, tile, marble and granite. They can be used for daily glass repair and home installation work. They are an indispensable assistant for your own hands in making flat holes, whether for beginners or professionals.