These nitrous oxide cream chargers are refills that contain food grade N2O safe for human consumption. Nitrous chargers come in 8gm and 16gm sizes, they are not standard and different sizes will fit different dispensers. Once they have been attached to the dispenser, they cannot be removed and reused. An 8 gram refill will produce 4 litres of nitrous oxide gas which will whip approximately one litre of cream.
The reason that these are used as a propellant for cream is because of the relative inert properties of Nitrous Oxide. It does not react with the cream or alter it’s flavour in any way.
If you are using these charges in an outdoor setting, then please be careful to take your litter home with you. There are so many of these small glass strewn around the fields at festivals it is like wandering through the field of some battle surrounded by spent bullet casings.