Features: The thread checker gauge set offer 27 standard and 23 metric precise machined aluminum gauges with color coded identification for frictions resistant durability in thread measurement applications. Features three size verification gauge marking, compartment screen printing, and stickers, while portable stored design ensures organized access to nut/bolts thread identification tool in tight workspaces. Ideal for professional mechanics, industrial technicians, and DIYer enthusiasts requiring accurate thread measurement for machinery maintenance, automotive repairs, or hardware organization projects. Quickly identify mismatched fasteners in workshops, simplifies bolt purchases at hardware stores, or sort mixed nut/bolts inventory in toolboxes using these thread inspection tool with double measurement systems. This comprehensive nut and bolts thread gauge set serves as both a workshop essential gift for tradespeople, combining aluminum construction with color coded sorting efficiency for permanent thread pattern verification. Specifications: Component:Aluminum Blue indicates the English size, red indicates the metric size Number of male and female thread: 50 A good helper for carpentry Package Includes: 50pcs/Set Thread Checker note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you donot mind befores you order. 2.Due to the differences between different monitors, the picture may not reflect the actual color. Thanks for your understandings.