I got this with my KWA M4A1 2GX and I have to say it is a great mag. It almost never misfeeds or double feeds. It seems to work flawlessly, but after having it for about 6 months now, I can see some flaws starting to appear.
-Finish looks and feels nice. /gray, not black
-Feels very sturdy, I haven't had any plastic break or metal dent.
-Feeds flawlessly most of the time. (One time it began misfeeding and rounds were dropping out of the barrel. I had to pull it out and put it back in. It has never double fed.)
-Finish has begun to wear. The paint has rubbed off on the bottom where I spin the wheel as well as where the mag makes contact with the inside of the magwell.
-Loose fit in my 2GX version of the KM4A1. Wobbles a lot. My friends also wobbles.
-If you wind it too much the mag will "reset" and after you fire a few round you will have to start winding all over again. This happens with my friends KM4A1 mag as well.
I won't buy another one of these mainly because of the wobble. The 2GX version of the M4A1 should fit most brands of M4 mags.
Rating: [4 of 5 Stars!]