The handle is made from bearing steel and the chuck from alloy steel. The tool set uses high-speed steel for thread cutting. This metric thread cutting T-type wrench set is built to cut bolts and screws with precision and durability. Designed for professionals and DIY enthusiasts, it enables accurate and consistent thread cuts on bolts and screws. Key strengths: - High-speed steel cutting tools for long life and reliable performance - Metric thread cutting capability across a wide range of applications - Hardened materials: bearing steel handle, alloy steel chuck Practical applications: - Bicycle repair and maintenance, including bolt replacement and thread repair - Furniture assembly and repair requiring precise, clean threads - Machinery manufacturing and maintenance, for creating or repairing threaded fasteners This set provides a professional-grade solution for precise thread cutting in diverse work scenarios.