Diamond Coating High quality diamond coating increases drilling speed and makes the drill bit sharper. Chip groove design Cut the edge to make it sharper and work more efficiently. Side holes make it easier to remove waste while dissipating heat when cutting material. Rustproof and durable. The surface is nickel plated for longer life and higher corrosion resistance. Universal round handle for electric drills and impact drills. Scope of application: The central hole makes drilling easier. Suitable for drilling glass, marble, ceramic tiles, limestone, fiberglass tiles, etc. Note: During the drilling process, water should be used to keep the drill bit dry to prolong the service life of the drilling tool. Dry drilling is strictly prohibited.