This cartridge is an essential component of Mammut's avalanche airbag system and must be ordered separately. This cartridge is completely compatible with the Removable Airbag System R.A.S. and Protection Airbag System, as well as with Snowpulse avalanche airbags from the winter season 2011-2012. Due to USDOT shipping regulations, we can't ship the full version of the cartridge to you, so you will have to get the empty version if you are shopping us from afar. To fill it, you will need to get a Cartridge Refill Kit and find a source of compressed air, like a local paintball or dive shop. We promise, all of this effort will be worth it when you survive that first avalanche.