This is not a core bit for drilling. It does not make holes, but it speeds up the cleaning of holes and strengthening of borders when borders are shredded or need to be clean. Features:1. Very useful to reduce the risk of cracking with standard and large-format tiles subjected to stress (ex tightened plumbing, led lighting, etc.), bevel beveling and tension softens rough holes in glass, ceramic and porcelain tiles.2. Strong alloy steel hardness, heat treatment, high strength, surface nickel plating, torsion-resistant alloy, to ensure a long service life.3. Use diamond core drill bits or diamond hole saw for grinder with a standard drill bit using a 5/8-11 or M14 shaft adapter. Specification:Style A: 5/8-11 threadStyle B: M14 thread Material: diamondSize: as sown (Note: 5/8-11 threads, usually suitable for North America market, please pay attention!)Package Included:Or 1 pc. * 5/8-11 or M14 thread. Or 1 pc. * 5/8-11 thread converter or M14 thread converter. Note: Please allow 0.5-1cm error due to manual measurement. Pls make sure you don't mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!