Well i Ordered this lightweight rail system recently and i don't have enough good things to say about it. It installs with ease, looks great, and does exactly what you want it to do. I also found the rail segments it came with to be the perfect length for whatever you wish to put on, whether a flashlight, fore grip, etc. And the fact that you can mount at any angle is great. Overall i would really recommend this rail system to anyone, especially people like me who like m4's but just don't really care for the rails biting into their grip.
On a side note, i would recommend making sure not to over tighten the two screws that secure the rail in place, as they can break. Also, make sure to use the included barrel nut, not the standard one already on your gun. Yes, this also means that you will need a delta wrench, so make sure that you have one before installing. And one more thing, I would recommend thinking ahead and installing the rail segments where you would like them to go, as they are easy to take off while the rails are installed, but putting them on requires you to take the rails completely off (or just a lot of frustration). I don't know if this was just mine, but after installing a AFG2 onto the larger of the rail segments, i noticed a bit of wobble between the rail segment and the AFG2 itself. I fixed this by using strips of hockey tape between them, but just wanted to let people know it could be a problem, but a very minor one at that. It shouldn't deter you from getting it.
Looks great, nice matte finish and trademarks
Installs easily, perfect fit
Very comfortable to grip
Modular rails, can mount anywhere
No gap between upper receiver and rail system
Not much to say con wise, but if anything i would have to say the slight wobble between the AFG2 and the rail segment, and also the re-installation of rail segments (having to take the whole thing off again)