General description Made of selected high-strength carbon steel and diamond-coated drill bit, this professional diamond hole opener offers excellent cutting ability, is rust-proof and durable, and provides high torque for a long service life. The diamond coating increases drilling speed and sharpness, while the cutting edge design reduces resistance for more efficient drilling, allowing you to create smooth, round holes accurately. A round chip hole on the side keeps the drill clean during use. Ideal for porcelain, glass, marble, ceramic, rock, and granite. Technical specifications Diameter: 25mm Material: High-strength carbon steel with diamond coating Usage Start by cutting a 45° angle to open the positioning crescent groove. Slowly erect the hole opener and drill at a uniform speed. Keep the bit moist while drilling to avoid overheating.