These LIONEL PART #72-2983-251 PHASE ADAPTER PLUGS are used to convert the output of the 180W Powerhouse to be in phase with other Lionel PowerHouse and conventional transformers. To determine if you will need these adapter plugs, turn over the 180W PowerHouses and look for the date code heat-stamped into the plastic bottom of the case at the corded end.  A date code number of 2000 48 or lower will require a phase adapter plug.

Set of two