PHITUODA 2 Inch / 50mm Diamond Drill Bits, Diamond Hole Saw Hollow Core Drill Bits for Glass Ceramic Porcelain Tiles Marble Granite Quartz Specification: Material: High-Speed Steel Color: Silver Finish: Nickel-plated Hole Diameter: 2" / 50mm Shank Diameter: 25/64" / 10mm Total Length: 2.18" / 55.3mm How to Use: 1. Put glass drill into the driller. 2. Because this hole saw cannot locate the center, so please cutting with it slowly with 45 degrees. 3. Please cut a small mark first to locate the center, then you can cut the material vertically. 4. The speed needs to be controlled, not too fast and water is required during cutting. Attention 1. When you using the diamond drill bits, please use lubrication (water). Otherwise, the diamond core drill will burn. 2. Please do not cut metal material with this tool. 3. Not for use on Concrete or for depths beyond about 1/2". 4. Please keep the speed within 800-1000 per minute, low drill pressure, and increased use of water lubrication will extend drill bit life. Warm Tips: 1. Due to manual measurement, please allow 1-2mm difference, thanks! 2. Our digital images are as accurate as possible. Because of the difference between the display and the light, the color is slightly different. Excellent & Sincere Service PHITUODA wants our customers to be 100% happy and satisfied. We provide an e-mail reply within 24 hours to handle product issues at our Amazon store. PHITUODA provides a full refund for any reason within 90 days after the date of purchase. What are you waiting for? Click the "ADD TO CART" button to see for yourself all the benefits of this amazing new product! Take advantage and buy it NOW!