The Automatic Reversing Unit (ARU) is used to continually run a train from point to point without operator intervention. The ARU comes with two Infrared (IR) sensors used to detect a train at different locations around your layout. This can be expanded to four sensors as well as interfacing to the TC-8S so that turnouts can be controlled enabling more complex routes can be repeated. Two adjustable timers control the length of time that a train is stopped for at each IR sensor.