If you are using the T4E licensed Walther PPQ for training in a high demanding environment, you need the T4E PPQ Quick Piercing Magazine. Like the factory magazine, the Quick Pierce design holds 8 rounds of .43 caliber paint, dust, or rubber ammo, but differs with the Quick Pierce CO2 puncture mechanism. Just install a fresh CO2 cartridge in the magazine and when you are read to engage, slap the puncture knob with your palm and the CO2 instantly punctures. This magazine also comes wth the proper spring for use with .43 caliber rubber ball ammo.