Left Hand Thread design: These fixing screws use a left hand thread, making them suitable for 1/2inch UNF and 3/8inch UNF drill chuck shank adapters and providing a secure, firm connection during operation. Metal construction: Made of quality metal, these screws are durable and longlasting, delivering reliable support and stability in drilling tasks. Two size options included: The set contains 5 pieces of M5*20mm screws and 5 pieces of M6*22mm screws to accommodate different chuck shank sizes and ensure proper fit. Easy installation: Precise dimensions and design allow quick installation. Simply tighten into the chuck shank adapter for a tight fit and smooth operation. Use scenarios: 1. Replacing worn or loose fixing screws on drill chuck shank adapters in metalworking or woodworking projects that use 1/2inch UNF or 3/8inch UNF threads. 2. Configuring tools in a workshop that requires reliable lefthand threaded fasteners to prevent loosening during reverse operation. 3. Working with equipment that uses multiple chuck shank sizes, utilizing the M5*20mm and M6*22mm options to ensure secure attachment across different adapters. Performance and compatibility: Designed to provide secure engagement with compatible drill chuck shank adapters, supporting stable drilling performance and reducing the risk of fastener loosening during use.