These channels are designed to be welded, riveted or bolted to the end of the rear part of the frame. To repair damaged frames. 3/16" inch thick and comes un-painted. This part has been discontinued by Toyota.
I got mine from BTB about a year ago. Other than them drilling and tapping the taillight holes wrong quality is good. They include spacers as they do not have the factory offset indent at the top like your OEM piece.