I make my own dial indicator rod extensions from 3/16 diameter O-1 drill rod. These can vary in length from 1” to 6” depending on the application. I hold a 4-48 die in the lathe tailstock die holder to cut the male end and cut 0.050” thread relief at the shoulder to provide a tight fit into the dial indicator. The female end thread is 4-48, threaded approximately 0.030” deep, and the first two threads are drilled out for a tight fit. Some examples of the various uses for the extensions include digital depth indicator extension on a small milling machine, hard to reach measurements with the dial indicator, and adding more travel length to a lathe carriage measurement where each extension is exactly 1” long. Thanks for looking.