When I purchased my Pro4X in February, I had the dealer add on the bed extender. I was told there was a one-day hold up to have that done because the dealer needed to get two of these gadgets. They are the end-caps for the bed rails in the truck bed. The dealership was going to charge me $100 for the two of these and said they were needed for the ends of the rails and in the bed, especially with the bed extender. I told them no-way was I paying that and told them I no longer wanted the bed extender and that I would find one on my own. Of course, that led to a conversation with the parts or service manager (can't remember which one) and they decided to throw them in for free. They made a "bid deal" about them "giving" these to me. Anyway, I removed them because I just installed two tool boxes in the bed of my truck (right and left side) and they got in the way. I won't say the manufacturer of the tool boxes, or where I got them because I don't want to sound like I am advertising for them (hate that). They are a great investment and mount in the rear of the truck near the tailgate on each side and swing in and lock out of the way over the fender wells. When you need them, a pull of a lever releases them and they swing out to the tailgate, so you can get at them. The bed extender won't work with them in place, but they easily lift out of the truck without tools and then you can use your bed extender if needed. I needed the toolboxes, I only occasionally need the extender, so win-win. Anyway, I got off course. I removed these to accommodate the toolboxes and are going to sell them on Ebay. Anyone familiar with these in the sense that they are in demand or really worth anything? Hate to have a potential $100 item laying around doing nothing when I can sell them for a fraction of that. I've included a photo.