Full-grinding and anti-rust treatment, clean and sharp without burrs, the drilling bits are anti-crack, wear-resistant and multifunctional. It provides smooth and accurate drilling in concrete, ceramic tiles, marble, thin iron plate, mirrors and glass while it is universal compatible common electric hand drill, bench drill. Made of premium alloy material, the the drill bit is durable, hard, sturdy and long-lasting. There are different sizes compatible your reference. It is suitable compatible woodworking, home improvement, drilling tools, hand tools, power tools, etc. Item Name: Drill Bits Material: Alloy Machine Drill Clamp Range: Above 10mm Features: Rust-Proof, Multifunctional, Universal Size Details: 3mm: Dill Bit Diameter: 0.3cm/0.12", Length: 7cm/2.76" (Approx.) 4mm: Dill Bit Diameter: 0.4cm/0.16", Length: 7cm/2.76" (Approx.) 5mm: Dill Bit Diameter: 0.5cm/0.2", Length: 7.6cm/3" (Approx.) 6mm: Dill Bit Diameter: 0.6cm/0.24", Length: 7.7cm/3.03 " (Approx.) 7mm: Dill Bit Diameter: 0.7cm/0.28", Length: 8cm/3.15" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 5 x Drill Bits (3mm, 4mm, 5mm, 6mm, 7mm)