I do not know who found this, but it works great for use as a 1/4 inch output jack tool for guitar or other musical instruments. Often, I cannot reach the "back side" of a 1/4 inch output jack when installing same in an instrument repair or modification. This device and a 1/2 inch box end wrench makes such an installation SO much easier! Once the nut is started on the output jack, slip the extractor into the 1/4 jack hole, and rotate slightly left to engage a firm hold. Then, with a 1/2 inch nutdriver to hold this tool in place and maintain the output jack position, one can tighten down the output jack nut with a wrench - without worry of problems due to "spinning output jack" syndrome. A tool with an original machinists purpose has new life with guitar technicians!