Product DescriptionEASY TO USE Center pilot tips are for wood, metal etc. Here is how you can keep the drill bit on target:a- You can make your own guide out of plywood - plastic or even cardboard. You just need to hold the bit in place until it marks the initial marks.b- It is possible to start drilling at an angle, with the edge of the bit forming a C-slot and then bringing the bit vertically .c- You can manually guide the bit with a damp sponge.Applicable industry: suitable for processing stone, tile, ceramic, glass and granite, etc.Package included: 1 * set of diamond drill bits Material: Iron,diamond plated on the headColorsilverQuantity: 15 pieces TIPPS: The electroplated diamond coating wears off if the tool overheats. Never let the bit dry out. Here's how to use water to cool the tool: a- You can build a mini water dam around the hole with plumber's grout. b- You can choose to spray water on the tip.c- Or you can use running water to cool the bit.Steps: Start drilling from the opposite corner, make a circular track with a C-slot, then slowly hold the drill straight. If you smell a burning smell, stop! Either you're too fast or you're putting too much pressure. Speed Kills: Reduced drill speeds, low drill pressure, and increased use of water lubrication will dramatically extend drill life. Warnings: do not use on concrete or for depths greater than approximately 3 cm; water is required for drilling for lubrication.7 Pack Multi-Material Tile Drill Bits,Double Cut Tungsten Burres For Rotary ToolsPremium Carbon Steel Diamond Drill Bits20Pcs Wood Carving Rotary Diamond Burrs HSS Router Rotary Burrs Milled Wood Bits Drill Bit MaterialCemented Carbide Tungsten Steel Steel, head plating is diamond Shank body is carbon steel and head is diamond plated High Speed SteelApplicable Material RangeGlass, Tile, Ceramic, Granite, Wood , cement walls It can be used for cast iron, cast steel, high carbon steel, chrome-nickel alloy, copper and other metals. Marble, jade, bone and other non-metals Glass, tile, marble, granite, ceramic Jade, stone stele, wood Wood, plastic how to useDrilling Engraving, flashing, deburring and other processing Drilling holes, available in 10 sizes Carving or Peeling Engraving , hollowing, grooving, polishing quantity7 pcs 10 pcs 10 pcs 20 pcs 20 pcs