This Robinair 7402 thread chaser will quickly restore threads to near original condition without the use of expensive thread-cutting equipment. Just tighten the tool slightly on the good threads, and then back off over the damaged thread area to restore the threads. The V-pads and dies are replaceable and comes with 6 dies for the following threads per inch - 4, 5, 6, 7, 7-1/2, 8, 9, 10, 11, 11-1/2, 12, 14, 16, 18, 20 and 24. Overall capacity is from 1-1/4 inch to 5 inch O.D.