Surefire makes them too.
Personally, I'd keep clear of the ProMag ones. They have a bad rep with most everything else, I doubt they finally got their mud in a ball with the S12 mags.
I like the OEM Izhmash mags, but they're 5 round only. If I felt the need for larger box magazines, I'd probably go Surefire. the MD Arms drum also seems to be the one to get if you're in to that kind of thing (I haven't bothered, but more power to those who are).
