The KB-1 is an external accessory for the Oberheim DMX drum machine, used to tune the eight voices individually, without the need to open the DMX front cover to reach the internal tuning adjustment knobs.
Comes with an attached two foot cable, with Molex connector that plugs into the mating CV connector on the back of the DMX.
 
The KB-1 is a powered unit, and includes a DC power supply that plugs into the back.
Optionally, you can make a minor modification to your DMX to power te KB-1 through the CV cable, eliminating the need for the external power supply.
See this page for details.