For: MagPul MBUS Gen.1 Rear Back-Up Sight (MilSpec Version/Black)Product Information:
Very great Iron Sight. Looks great on my SCAR. I wasn't disappointed in the quality of the sight. Looks and feels very durable. The two aperture sights are hard to switch but you will rarely use the small one.
Small con: To switch the sights is a little hard.
But other than that, its really good and worth it!