The Powermaster converts the electronic signal from the handheld legacy controller to an analog signal. You will need a Powerhouse transformer and the Powerhouse for each track. I have two separate tracks I run under our Christmas tree, so I run two transformers and two powermasters with my legacy controller. it's a little overkill but I didn't buy any fasttrack switches for this year. There is occasionally some lag, especially when switching between trains quickly. Nothing horrible, but there can be some lag. The latest Legacy controller works well and is really good with the newer locomotives. You have control of absolutely everything. You can even turn the cab lights on and off on some locomotives.