[EXTREME HARDNESS] These diamond drills are made of industrial carbon steel with a plated coated body to resist corrosion. A thickened diamond coating on the tips provides superior cutting strength for maximum drilling performance. [EXTRAORDINARY SHARPNESS] Each diamond bit has a precise finish that reduces incision resistance and drill pressure, increases efficiency, and enhances water lubrication effectiveness, enabling clean and precise holes on glass or ceramic surfaces while significantly extending drill bit life. [CLEARANCE HOLES] The design along the drill bit facilitates the entrance of cooling water and the escape of debris and particles during drilling, making the process smoother and more efficient. [WIDE USAGE] This glass drill bit set includes 5 sizes (4mm / 0.16 inch, 6mm / 0.24 inch, 8mm / 0.31 inch, 10mm / 0.39 inch, 12mm / 0.47 inch) to meet various drilling demands. Ideal for drilling glass, tile, porcelain, ceramic, brick, and stone. Length: about 2 inches Color: silver Material: carbon steel Size: 10 x 6 x 3 cm Package Contents: 5 x Diamond Coated Drill Bits Note: Please keep the speed within 800–1000 RPM. Low drill pressure and consistent use of water lubrication will extend drill bit life. Continuously apply water during operation when drilling glass or ceramics. The package includes only the items listed above. Lighting and monitor differences may cause slight color variations between the image and the actual item. Measurement allows an error of +/- 1–3 cm.