The size of the cartridge depends on the size of the airbag vest. The size is indicated in the vest where you insert the cartridge as well as on the label of the cartridge, in the user guide and on Heliteus.com.
CAUTION: Only Helite cartridges may be used for Helite airbag vests. Other brands cannot guarantee optimal performance or proper deployment. Helite is not responsible in the case of dysfunction.