i have the under cover flex, i purchased it in combination with the pop-n-lock tailgate lock and amp research hd max bed extender. All three work together well as a storage, cargo management system. Only thing i thought was a pain in the rear was how much went into aliging the flex the right way. if pushed to far off to one side, the slam latches would work on one side and wouldnt latch onto the other. I was reading on a few other various forums and saw where people would use washers as shims to space the rails slightly further inwards to allow to latches to slam better, anyone else have any experience with this?