Simply screw the cartridge in tight and then push the head onto the valve, unscrew the cartridge half a turn to release the CO2 cartridge.Features 1pc threaded 25g CO2 cartridge and shell included.Key Features:Material: CNC aluminumCompatible: Presta / Schrader valvesSize: 2.7 x 2.8 x 1.5cm (NANO AIRBOOSTER L)Weight: 12.6 g ( NANO AIRBOOSTER L )124 g (with 25G cartridge and shell)