Futaba Trainer cord - square plugs both ends.

For use when the Futaba 8FG or 12FG is used with another Futaba
transmitter with a micro port and standard 9.6V battery
are used together.
Micro connectors on both ends
Fixed directional hookup is labeled "T" for teacher side and "S" for
student side to insure proper connection

Trainer Cord for the Futaba 12FG or 8FG and instruction sheet

Connecting between transmitters

Length: 9.9' (302cm)

This cord uses voltage drop circuitry. This will NOT work, nor
can it be modified to work with any other standard
radio systems.