What you will get: there are 20 pieces of diamond drill bits in the package, which are sufficient to meet your daily use and replacement needs; You can also share them with your family and friends who love handicraft or who have a job of handicraft Quality material: diamond hole saw drill bits are made of high strength carbon steel, which makes these diamond drill bits and precise, not easy to deform or wear, providing them with a more pointed and a longer service time Great design: diamond coated drill bits are finely made and have a smooth ; Side chip removal holes are designed for easy removal after drilling to improve the speed of drilling and the work more efficiently Wide application: you can safely use the hollow core drill bit, which has a wide range of applications and is suitable for drilling holes of different materials, like glass, tile bottles, blocks jars, fiberglass porcelain tile ceramic, marble, light stone, etc. Size design: this hole saw drill bit is 1/2 inch/ 12 mm