The contoller is necessary for sets #4558 and #4565. It includes a transformer with an integrated electrical plug and wiring to connect to the track. The connectors just snap onto the outside of the rails so you can connect power almost anywhere, straights or curves.
You can adjust the speed anywhere from standstill to full speed in either direction. It has a green LED to show when the power is connected. There are no additional 9V outputs on the controller (there were on the old 12V controllers which is why I mention it.)| UK Name: | Transformer and Speed Regulator | US Name: | Train Speed Controller |
| Pieces: | 3 | Available: | 1991- |
| Minifigs: | None | Price: | $40 (S@H $46) |
| Electric System: | Controller | Alternate Model: | No |