General description AlwaysH 30pcs Diamond Glass Countersink Drill Bits are designed for use with most professional electric drills. These versatile bits are ideal for replacing nail drill bits and can be utilized for various applications such as carving, grinding, and engraving on a wide range of materials. Made from high-quality materials, they ensure a long service life. Technical specifications Quantity: 30 pieces Diameter: 2.5 mm