This is a heavy duty 2 way trailer link. The coil has 2 shielded cores which helps prevent cross-talk between the 2 channels. The sockets must be installed onto a flat surface to obtain a waterproof seal. The coil connects and locks via a ring you twist. They are suitable for reversing camera systems using the 4 pin aviation style connectors.
Both the plus and sockets are wired up the following way:-
pin 10 - black (negative)
Pin 12 - Bare shield (negative - the shielding surrounding the video cores)
Pin 8 - red (positive 12v)
Pin 6 - White (video 1)
Pin 13 - Yellow (video 2)
This is the same as on the socket or coil.