These are installed on the caravan, this one is for a single axle caravan, and then you have a remote control unit allowing you to move the caravan under its own steam into very tight locations without needing the car.
This is a link to the Purpleline website, so you can see how it all works; http://www.purpleline.com.au/products-titanium.php
this unit is new in the box and has never been installed.
They usually sell for around $1,500.oo
I am selling this one for $950.oo
Please feel free to ask questions, the unit is located in Bayswater, Victoria