Feature: 1.Every product has a unique Manufacturing Part Number label on the inner package that proves it has been qualified,which include Part Number,Model Number and inspection date information;2.If you have any questions about the item,please provide us the Manufacturing Part Number for checking,your profits will be guaranteed.3.High quality,durable use.4.Great tools for making an accurate hole on various bowlder, agates, pearls, jade, etc.5.Use Tip:Light pressure, diamond tools are processed by grinding the workpiece, If use too muchstrength, flour is not easy to rule out, especially the small tools is also easy to damage.Warm reminder: Drill bit generally need to be drill slowly on the stone when start to drill, wait for the stone to open hole and then drill hard. Like hard stones, or ice types, miscellaneous stone, agate, etc., the punch needle may not be durable. If it is used on hard stone, it is recommended to add emulsified oil to lubricate the Drill bit.Specifications:Material: Diamond+SteelColor: SilverBrand Name: Shank Diameter: 2.35mm/0.09inchHead Diameter: 1mm/0.04inchSand length: About 17mm/0.67inchFull length: Approx. 42mm/1.65inchSize: 42 x 2.35MM/1.65x0.09inch( L x Dia) Weight:10gPackage Include:10 x Diamond Coated Hole Saw Drill Bits