These are extension cords for Kato Unitrack. I like the positive connection built into the cord ends. Prevents accidental disconnection.

Ended up with lots of Kato Feeder Cable connectors when constructing a permanent layout. Upon deciding to make another, but temporary layout, wanted the matching connector end for connection to the DCC base station. While Kato makes a single mating connector cable, selected this since either one would be shortened, ended up with a spare connector for use elsewhere.