1.MATERIAL: This set of drill bits is made of galvanized macadamia material, which is wear-resistant, durable and long-lasting. High hardness and sharpness. 2.Scientific design: the diamond drill bit adopts scientific chip design to make the diamond drill bit set more stable, and the diamond tile shank adopts round design, which is widely used in electric hand drills and suspension grinders. 3. Unique details: diamond coating can increase drilling speed. Round shanks are compatible with most machines, such as hand drills, diamond sanders and stripping drills. Side grooves help to remove dirt and drill holes smoothly and quickly. Depth markings are useful for precise construction. 4.WIDE APPLICATION: Tile drill kit is perfect for drilling holes in glass, tile, granite, marble, limestone, quartz, terrazzo and other hard materials. Our diamond drill bits for tiles have multiple diamond slices that act like cutting teeth, so they work exceptionally accurately and quickly and won't break or fall off. 5.PACKAGING AND SERVICE: 5mm, 6mm, 8mm, 10mm and 12mm drill bits are included to meet your different needs.