Yes, they are the power leads. They have banana-plug style connectors that plug into the ends of the hollow outer rails. I got them, but like others have said, a set of alligator clips would work too. If you want to support all wheels on a big steamer with a large tender, you might need the extra rollers. Or a large, draw-bar'd consist you don't want to break up. Note, the roller stand is useless for speed matching, since all rollers roll independently.