The superb WE Hi Capa CO2 5.1 magazine. Holds 31 rounds. Contrary to urban belief - CO2 magazines are not 'over powerful'. They are actually more consistent though various ambient temperatures and less likely to freeze. Please note that the base plate is held on by a clip which needs to be lifted up to remove the plate without damage.
With all CO2 magazines they do suffer from seal failure due to the high pressure produced by the CO2, they can and will fail at some point in the future. This could be a while but then it could also be fairly soon.
Also fits Tokyo Marui Hi-Capa 5.1 Match Custom.