This is actually the first ar15 I ever bought I just kept adding to it through the years. I actually took the rear iron sight off of the m16 upper I had and put it on this. I believe it’s the same rear sight the army uses I replaced the sight on the m16 upper with an iron sight the marines use. The 37mm launcher on the bottom is pretty much just for looks. I have shot some flash bang rounds out of it already and even though it’s pretty much just a fire work. They work very well at night, I had to test out how bad it would be looking at one when it went off so I shot it straight into the air and when it went off I couldn’t really see anything for a good 10 seconds and even after my eyes had adjusted back to the dark I still had a spot in the center of my vision.