[Main Function] 42pcs Thread repair kit includes 21 dies, 19 taps and 2 thread files are applied to creating new threads or repairing damaged threads on most metals such as cast iron, steel, aluminum and copper. It can easily help you repair damaged external and internal threads on nuts, bolts and studs. [Rethreading Dies*21] The hex drive head makes it quick and easy to use with a socket and a speed handle. This hex head is also helpful in tight, hard-to-reach areas. Inch coarse sizes: 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8"; Inch fine sizes: 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8"; Metric sizes: 6x1.00, 8x1.25, 10x1.25, 10x1.50, 12x1.25, 12x1.5, 12x1.75mm. [Rethreading Taps*19] The thread restorer kit is great for cleaning up crusty, rusted and damaged threads. Gold/Black/Silver taps, just different finishes to help you keep things organized. Inch coarse sizes: 1/4", 5/16", 3/8", 7/16", 1/2", 9/16"; Inch fine sizes: 1/4", 5/16", 3/8", 7/16", 1/2", 9/16"; Metric sizes: 6x1.00, 8x1.25, 10x1.25, 10x1.50, 12x1.25, 12x1.5, 12x1.75mm. [Thread Files*2] Professional thread repair tool parts are made of high quality carbon steel material, highly tempered for strength and durability. SAE size: 9,10, 12, 16, 20, 27, 28, 32 ; SAE size: 11, 12, 13, 14, 16, 18, 20, 24mm. [Easy To Storage] All thread repair tools are stored in the Thickened blow-molded box which is duarable,anti-extrusion without deformation. The groove in the box can protect thread repair tools well and easy to store.The thread chaser kit has the most common sizes in UNC, UNF, and metric. Cleans internal and external threads. Each of them are marked with size which can provide a quick reference and easy to find.