Proto Matrix Rail
Black Aluminum back cap
Everything else stock.
Won't strip on you like the plastic one.
Well theirs not much to say about this thing. I was forced to get it because my first backcap stripper and the bolt shot out the back and completely destroyed the threads on the cap. So I got this thing and it hasn't stripped on me and probobly won't. Thats a 10 in my book. I say you should get this before you get any other up so the same thing that happened to me the first time won't happen to you
Huge advantage over the plastic backcap, because it won't strip in the middle of a game and force you to call yourself out =)