I was organizing my MX trunk storage, and I thought to check out the mobile charger and what is in the case. I found the three standard attachment the mobile charger itself. I opened the back zipper of the case, I found this hook like rod. I'm not sure what that is and what it is used for, there is no mention of it in the manual. the only thing I can think of is that it is used for towing, if so, where do I screw it to? below is the image of the rod. Thank you.