[Quality Material] The steel after heat treatment has high hardness and black oxide coating on the to prevent rust. It is and not become dull after hundreds of times of use. [Thread Repair File] Designed to repair damaged external threads on studs, bolts, screws, pipes and fittings. [Easy to Use] Suitable for left-hand or right-hand thread. The operation is simple, a few minutes of work can allow you to easily fix the thread and tighten the nut. [Comprehensive Set for Versatile Use] This thread repair file set includes both SAE and metric thread files, making it suitable for a wide range of applications. The SAE files cover sizes 9, 10, 12, 16, 20, 27, 28, and 32 TPI (threads per inch), while the metric files include sizes from 0.75mm to 3.00mm [Thread Repair File Handle] The handle can be turned over, the detachable rubber sleeve is easy to slip off, and it can be switched as Only suitable for external threads, not for internal threads., Manufacturer: Akfldms