Lang Tools, 7-pc UNC thread restorer die set

For internal threads. 7-pc UNC (coarse threads). Incl. 1/4"-20 5/16"-18 3/8"-16 7/16"-14 1/2"-13 9/16"-12 5/8"-11. Used to restore damaged internal threads. This are special threaded restoring taps that ensure a good result and they are safer in restoring threads than using regular thread cutting taps and dies. Regular cutters are sharper and can easily further damage existing threads. Packed in a re-usable clamshell package. USA made. Note: Not suitable for cutting new threads.