The Digital Electronic Control second station main harness connects the main station control box with the second station control with the help of a secondary harness. The second station main harness has one 6 pin, one 4 pin, and one 3 pin connections on each end. One second station primary harness is required per engine when rigging a second station. For use with current Command Link controls ONLY because of a different style 3 pin connector. Because of the different 3 pin connector, an adaptor harness will be required when a Command Link Plus main station is connected to a current Command Link second station.