Features:* Install the hole opener on an electric hand drill or a small bench drill use it.* Because this kind of hole opener does not have a central positioning drill, the hole opener should be tilted to 45, the speed of the electric drill should be slowed down, and the glass stone should be slowly tilted.* Do not open too quickly. It is necessary to continuously add water to cool the opening device.* During drilling, water cleaning is needed to cool the drill bit. Good cooling can greatly extend the life of the hole opener.* Do not use the drill bit without water, otherwise the drill bit may be damaged.* It is recommended to hold the drill bit deeper. If necessary, you can cut off the drill bit to make it shorter to reduce shaking and not easy to break.*The drilling speed must not exceed 6000 rpm, because the drilling speed is too high, the drill bit is easy to break. Specifications:Product Name: Mini Micro Drill BitsMaterial: Stone Diamond Length: 40mm (Approx.) Shank Diameter: 0.6mm Drilling Diameter: 1mm Color: Silver Suitable for: Jade, Marble, Crafts Quantity: 20 PcsPackage Contents: 20 Pcs Mini Micro Drill Bits Note:1. The actual colors of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness.2. Please allow slight manual measurement deviation for the data.