This scope is amazing. I got it today for my ECHO 1 G36C and it is DEAD accurate. It's full metal i think, and the guy i bought ti from uses it on his real guns. It has a green and red dot, with 3 settings for both.
Battery life is about 3-4 hours non stop, but i wouldn't test it, and it comes with 2 batteries! Just to let you know though, don't adjust it too much, because it can break. So if your looking for an affordable red-green dot scope, look no further than this. Also it comes with the adjustment tool in the package.
Easy to adjust
2 types of rail settings
Only one i can think of is that the adjusting wheel is really tight on mine, but it's almost a good thing, because it probably won't accidentally turn on wherever you put it
Another i gues would be the for smaller rails, like on my gun, the scope can kinda move forward and backwards because there aren't any notches to hold it in place, but don't let these things stop you from getting this scope, you will not regret it!