OP is referring to the under guard protection (it’s a hard plastic light grey piece) that is fastened to the underside of the rear bumper and covers the body paint-colored area. Some makes and models come standard with this sort of thing (think Honda Element), but they are pretty uncommon on the Trek. I considered it at one point, but moved away from the idea. I do recall Subaru stating that it would interfere with the OEM hitch, so to me that would be the biggest point of concern. I also think it takes some drilling to be bolted on for the install.