It's a Cargo trailer with a small rooftop type container... used to hear more about them but I think most found out it was cheaper to get a harbor frieght trailer and cartop carrier separately and assemble themselves.
No idea what bike the OP has so until more info is provided, hard to give any bike specific info.
Here's an article for the ST1300:
A member on this forum asked if I could provide him with some information on how to connect a Electrical Connection Trailer Isolation Relay on a ST1300. I decided to draw a little wiring diagram with the correct color codes to make it easier. For those who are not familiar with isolation...
www.st-owners.com