The Beta C-Mag is a 100-roun capacity STANAG Magazine designed for rifles and submachine guns firing the 5.56 x 45 mm NATO, 7.62 x 51 mm NATO, and 9 x 19 mm Parabellum cartridges. C-Mag is short for century magazine, referring to its hundred-round capacity. It has two drum units, each of which hold half of the cartridges inserted into the magazine. The latest version of the magazine features a transparent backing to allow the user to see the number of rounds remaining in the magazine. A C-Mag weighs about 2.1kg when loaded with 5.56 x 45 mm ammunition.