Well, the Beta C-Mags are 100 round drums, they utilize the twin drums that feed the weapon together ([url=http://upload.wikimedia.org/wikipedia/commons/0/04/Double_drum_magazine_filled.svg]Here's the basic load design of one from the back[/url]). I was considering a 200 round box, but I couldn't really decide on how many would be carried, so went with a few 100 round drums instead. I can change that, no problem, if you want though. It won't bother me either way.