The Alpride Cartridge is compatible with all avalanche backpacks with integrated Alpride avalanche airbag. In a situation that hopefully wont happen, after the cartridge of the avalanche backpack has been triggered and needs to be changed, this lightweight set offers the perfect replacement for the unit. The two cartridges cannot be filled again, theyre simply discarded. The cartridge is the same kind as that used in aircraft lifejackets. So, according to IATA regulations, they need to go in your luggage on powder trips to distant countries!