Durable Material: These diamond drill bits are made of high-strength carbon steel with a nickel-plated surface to extend service life. The cutting edge typically lasts six months to one year before resharpening is needed. Clean and Smooth Cutting: The diamond hole saw is coated with high-quality, uniform diamond particles to increase drilling speed and precision. It provides smooth cuts without chipping, delivering excellent cutting performance. 10 Different Sizes: The drill bit set includes 10 sizes: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 18mm, 32mm, and 50mm. The variety of sizes meets most common drilling requirements. Side Opening and Laser Marking: Featuring a side spline hole design that allows efficient removal of debris during operation, keeping the bit clean. Laser-engraved size markings provide clear, durable identification that resists wear. Wide Application: Compatible with standard electric drills. Suitable for use on hard materials such as marble, porcelain tile, glass, ceramic tile, concrete block, and granite. When drilling hard materials, use water lubrication to help prolong bit life. Contents: 10 diamond drill bits