Features: 1. Each product has a unique manufacturing number label on the inside. This number shows that it has been approved and includes the part number, model number and inspection date information. 2. If you have any questions about the item, please tell us the manufacturing part number to check. Your benefit is guaranteed. 3. High quality, durable to use. 4. Great tools to make a precise hole in different bowls, agates, pearls, jade, etc. 5. Use tip: Diamond tools are worked at low pressure by sanding the workpiece. If too much force is used, the flour is not easy to discard, especially small tools can be easily damaged. Specifications: Material: diamond + steel. Colour: silver. Brand Name:Shank Diameter:2.35mm Head Diameter: 1.5mm Sand Length: About 17mm Total length: approx. 45mm Size: 45 x 2.35mm/1.77" x 0.09"(L*Dia) Weight: 10g Package Includes:10 x Diamond Coated Hole Saw Drill Bits Reminder: Usually the drill bit needs to be slowly drilled into the stone when you start drilling. Wait until the stone opens the hole and then make a drill. Such as hard stones or types of egg, various stones, agates, etc. the needle may not be durable. If used on hard stone, it is recommended to add emulsified oil to lubricate the drill bit.