Obviously it's not really a "BUIS" since it's made of polymer, but you get the idea. I am looking to sell my Magpul rear back-up sight. It is in like-new condition, but does not come with any box. I will post a picture later but chances are, if you're looking at this ad, you know what it looks like. I am willing to consider trades of equal value. Things I'm looking for: Brass-cased .45ACP ammo and brass-cased 5.56/.223 ammo. Face-to-face, cash-only in the Portland area. Thanks for looking!