HIGH QUALITY DIAMOND DRILL BIT SET with RUSTLESS, CUTS QUICKLY - Made from high strength carbon steel with nickel plating surface makes these drill bits durable and precise The bit's tip head is made of 80 grit diamond coating, which is uniform It great helps to increase the drilling speed and more sharper than other ordinary hole saws. 10 PCS MOSTLY USED SIZD - 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 drill hole on glass, marble, tile ,blocks jars, fiberglass porcelain tile ceramic, slate mable, granite light Stone etc. Will work with all electric drill and impact drill. NICE DESIGN - The center pilot holes and side holes help to remove the waste material easily;And surface nickel plating, extend the service life, enhance the surface corrosion resistance Kind Notification - When cutting hard materials it is important to ensure the cutter is kept cool to avoid damage to the material being drilled and premature wear of the cutter; Water is required for lubrication when drilling, which can extend the life of the drill bit set.