The CZ75 D Compact Spare Magazine is a 16 round mag for the CO2 GBB airsoft gun. This full size mag carries extra ammo, as well as it's own CO2 cartidge. This delivers full power with each magazine change.
The CZ75 D magazine carries the CO2 powerlet, instead of housing the CO2 in the gun. This makes the mag a little better fit in most pistol mag pouches, and also reloads the CO2 cartridge with every magazine change.