" High Quality Diamond Drill Bit Set with Rust, Fast Cut - Made from high strength carbon steel with nickel plated surface which makes these drill bits durable and precise. The bit head is made of 80 grit diamond coating, which is uniform; it helps increase drilling speed and sharper than other regular hole saws. Most Used Sizes 10 Pack: Includes the following diameters: 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 50mm. Using laser marking, the size will meet most of your different needs. Application: Suitable for use in drilling holes on glass, marble, tile, fiberglass pots glass, porcelain, ceramics, slate, granite light stone, etc. Works with all power drills and hammer drills. Nice design - Center holes and side holes help remove trash easily; and nickel-plated surface to extend life, improve surface corrosion resistance Note: When cutting hard materials, it is important to ensure the cutter is kept cool to prevent damage the material to be drilled and premature wear of the cutter. water is needed for lubrication when drilling, which can prolong the service life of the drill bit set. "