I got this thing to try and get myself a less cluttered field of view on my M4, as I personally don't like ironsights. I've totally fallen in love with this reflex and have not had any problems with it! If you're looking for one, I totally advise either this one or its sister Black Ops version. It also includes the two hex keys needed, an extra battery, a buff cloth for cleaning the lens, and a lens cover for when not in use.
I should also mention that both mounting hex screws and both adjustment hex screws are METRIC
+ Slim and lightweight.
+ Not made of plastic
+ Easily adjusted
+ Gives you a nice open view of what is going on around you
+ Changeable reticles and brightness settings
+ Looks awesome!
Possibly the only con I can think of is that the smaller allen wrench included with mine was bent weird, but I have plenty of allen wrenches so it wasn't a problem.
I also kind of wish it mounted on with thumbscrews but that would be pointless anyway. Even if it loses power & you can't replace the batt, the lens works as a general ironsight on its own.
Rating: [5 of 5 Stars!]