Eurorack modular synthesizers use IDC connectors to distribute power. They are 16 pin 2x8 male headers, or 10 pin 2x5. In each case, there are two columns of pins, #1 on the right, with 3, 5, 7, ... above it, and 2, 4, 6, 8, ... on the left. Pins 1 & 2 are shorted together to supply -12V; pins 3, 4, 5, 6, 7, 8 supply GND; pins 9 & 10 provide +12V. Some companies only use these 10 connectors. On a 16 pin version, pins 11 & 12 provide +5V, and the remainder are used for a control voltage and a gate. The +5V can be useful, but the CV and gate not so much. Female connectors are pressed on to ribbon cable to mate with the male headers. I wanted a way to test cables and power distribution bars, to ensure the correct wires are connected, and no unintended shorts have occurred.