I'm breaking in a new Smart Alec and was wondering as to the intended purpose of an extra clip on the shoulder straps. It's roughly S-shaped and on the same band of fabric that holds the sternum strap clips. I don't see it in the photos on the product page or mentioned in the description. My best guess is that something is intended to snap into the clip, but I'm afraid my imagination has failed in figuring out what. Can anybody clue me in?