DRILL SPPED: The speed of drilling machine need to be reached 2000 RPM when you use our drill bits to drill holes. OPERATION: The higher speed of drilling machine, the better effect of drilling bits, please use cold water during the drilling hole operation. MATERIAL: The diamond drill bit is made from diamond powder, high-quality, precise and durable to use. WIDE USE: Idea for drill holes on the jewelry, ceramic, jade, agate, glass, amber and semiconductor materials etc. PACKAGE: Set of 20pcs 1mm diamond drill bit. Descriptions: Our lapidary drill bits are made from diamond powder, precise and sturdy. It is perfect for drilling holes on the jewelry, ceramic, jade, agate, glass and amber etc. Using high-speed of drilling machine to drill will to a good drilling effect. Please use cold water to drill. Our drill bits are very sharp and you could use them for many times. It is a good drilling tool for you to choose from. Please Kindly Pay Attention: -Use cold water during the drilling hole operation -Use high-speed(Up 20000 RPM) to drill holes with our drill bits. -Be stable, don't shake Specifications: Condition: 100% Brand New and High Quality Material: Diamond Powder Color: Silver Length: Approx. 36mm Diameter of Shank: 0.6mm Diameter of Head: 1mm Weight: Approx. 4g Quantity: 20PCS Package Included: 20 x Lapidary Drill Bits