CO2 gas cartridge / 4 cartridge sizes (18, 20, 24 and 33 g) provide effective protection regardless of the volume to be inflated in the airbags, depending on the size of your protective vest. For the size of your cartridge, refer to the label on your X'AIR SAFE protective vest. Adult sizes : XXS, XS, XST : 18g / S : 20g / ST, M : 24g / MT, L, LT, XL : 33 g. The cartridge is easily and quickly replaceable by yourself. freejump cartridges are covered by a 4 year warranty.