EMG Ultrajak system;
I believe this item is no longer made-in the package and unused
This hard to find item solves a lot of problems when one is trying to wire up two acoustic pickups running to a single output jack.
various possiblities exist for power supply to one or both pickups,
running two pickups out in stereo or combining to mono...saves running a second output jack much of the time depending on your needs
also uses an innovative expanding ball bearing using an Allen wrench that grips the jack hole which eliminates the need for a nut and washer on the inside.