The perfect glass drill bit! Great for Home Projects Smooth and Efficient Drilling Diamond coating maximizes drilling performance and retains a sharp cutting edge after multiple applications. Versatile Uses,Set includes commonly used sizes that is great for home and professional use all around the house. Great to use on multiple types of materials including glass, plastic, and ceramics If you're a regular user of diamond drill bits it is worth having a combination of both small diamond drill bits in your tool box as sometimes you don't know if you have a very tough material until you start drilling! Perfect set for cutting accurate holes in a wide variety of materials such as glass and ceramics These diamond drill bits made of high-speed steel that is durable and have a long sevice life,which are high quality and good performance that excellent for making clean and accurate hole. Please keep adding water when the diamond drill bits are working on the glass or ceramics.low drill pressure and increased use of water lubrication will extend drill bit life. The perfect marble drill bit! Nickel Plated for Extra Durability Each bit is coated with an extra layer of nickel for protection against corrosion after multiple use. When you using the diamond drill bits, please use lubrication (water),otherwise the diamond core drill will burn.Not for use on Concrete or for depths beyond about 1/2". Need to pay attention when using! Sharp&Smooth Cut - Coated with high quality diamond, the diamond hole saw creates a high precision, smooth cut with no broken edges. Reduced drill speeds, low drill pressure and increased use of water lubrication will extend drill bit life considerably Note - When you using the diamond drill bits, please use lubrication (water),otherwise the diamond core drill will burn.Not for use on Concrete or for depths beyond about 1/2". Electroplated diamond coating will wear off if the tool gets too hot. Never let your drill bit run dry Here is how you could use water to keep the tool cool: 1.You can build a mini water dam around the hole with plumbers putty. 2.You can choose to spray water on the drill bit. 3. Or you can use running water to cool the drill bit. Diamond coating maximizes performance and retains a sharper cutting edge than traditional carbide or bimetal hole saws Center pilot drill bits are for wood, metal, etc.; Here is how you can keep the drill bit on target: 1. You can make your own guide out of plywood - plastic or even a card board. All you need is to keep the drill bit in place until it makes the initial marks. 2. You can start drilling at an angle, with the edge of the drill bit making 3. C slot and then getting the drill bit up to vertical. 4. You can manually guide the drill bit with wet sponge. ✔ Ideal Application - This diamond coated core drill bit removes a complete circle from glass, marble, tiles,granite, ceramic or other.They are perfect for drill glass, tile bottles,blocks jars, fiberglass porcelain tile ceramic, slate , granite light stone