Each unit has three inputs and one outputs. The upper unit's output is normalized to the bottom unit's input, allowing you to use the module as a 6-into-1 OR combiner.
The module is entirely passive and due to the diodes used in the circuit there's a voltage drop of 0.7V between the input and the output.
Each unit: 3 inputs, 1 output
3U Eurorack module, 2HP wide, 18mm deep