<p>High quality diamond drill bits with thrifty, fast cutting surface Made of high strength nickel plated carbon steel makes these drill bits durable and precise; the tip bit of the head is made of 80 grit diamond coating, which is uniform; it contributes a lot to increase the drilling speed and sharper than other ordinary saws.10 pcs mainly used sizd Contains the following diameters: 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 50mm; Using laser marking, the size will satisfy most of your different needs. Application Suitable for use in a drilled hole on glass, marble, tile, block jars, fiberglass, porcelain and ceramic tile , granite light stone, etc. It works with all electric drill and impact drill.Nice design the center holes and side holes help easily remove waste material; and nickel plated surface, prolong life, improve surface corrosion resistance type of notice when cutting hard materials, it is important to ensure the cutter is kept cool to avoid damage to the material to drill and premature wear of the tool; water is needed for lubrication when drilling, which can prolong the service life of the bit set.</p> <p>Note: The data is all measured manually, please allow 1-3cm error, due to the difference in light and display, there will be a certain color difference, the actual object received shall prevail.</p>