Allows a second port for the communication cable connection to the ThunderMax It is installed to the bikes wiring harness at the 36-pin ECM connector (connection requires harness plug disassembly; two terminated wires are inserted into two unused ports in the 36-pin connector, and a ground wire added) Handy for motorcycle models with tight clearances around the ECM such as Dyna, Softail Rocker and V-Rod models Works with ThunderMax ECM with AutoTune Closed Loop System 711-953; Note: Requires ThunderMax ECM with mini USB communicator port. Will not work on previous model ThunderMax ECM.