Full instructions for this equipment can be downloaded from the following link - http://www.hornby.com/us-en/downloads/view/download/item/148
Can be fitted to a model railway layour as an addition to supplement an existing controller by provider extra track power. Can also be used to automatically handle track polarity reversal when connected to a Reverse Loop, triangle permanent way sections and Wye track configurations.
Will also boost the digital signal from a R8213 Select or R8214 Elite (or any other DCC controller)
More than one R8239 can be joined together