it looks like it might be an extang cover.....on the tailgate bar there should be 2 little things u push in on either end thatll let u pop the the tailgate bar up and then roll it up......the cover looks like its one of those ones where theres a groove on the bar and on the cover and they fit into one another by pulling the cover over the bar....hope it helps...

 

http://www.extang.com/docs/saber.html

 

that looks like it!

thanks