The Major Paintball 12 Gram CO2 Cartridges Case of 450. These cartridges have both high quality specs and a low cost. Each cartridge's weight is measured while being filled and sealed, instead of just pressure equalized with the fill source which can cause flash fills. Translation: each cartridge has the same amount of CO2 inside! They are constructed of high quality steel alloy to maximize durability for paintball players who like to dive roll with their CO2 in a wrist band. Good steel quality also means a thinner cartridge wall which reduces overall weight.