Ideal for restoring damaged or worn external threads on bolts and pipes. Thread restoring files can be used with 8 different thread sizes, allowing you to find a true fit effortlessly. 4-piece set offers 4 convenient file sizes for quick and effective application. Color caps on tubes help identify the file type, so you can select the tool you need with ease. Type 1 black cap: regular bolt; 11, 12, 13, 14, 16, 18, 20, 24 TPI. Type 2 red cap: extra-fine/extra-coarse bolt; 9, 10, 12, 16, 20, 27, 28, 32 TPI. Type 7 green cap: regular pipe; 8, 10, 11 1/2, 14, 16, 18, 24, 27 TPI. Type 8 blue cap: metric bolt; .80, 1.00, 1.25, 1.50, 1.75, 2.00, 2.50, 3.00 mm. Includes pouch for storage and organization.