These are a great middle ground between a full size 2.6kg or 6kg CO2 bottle and disposable 16g canisters.
They are still light and thin enough to be portable or to fit in your fridge for carbonating home brew but they hold the equivalent of 25 x 16g canisters. Enough to dispense over 100L of beer or carbonate and dispense about 50L of home brew.
They also work out much cheaper than using the disposable canisters at about $21 a fill (Soda Stream offers a swap and go service in most towns and suburbs in Australia, see a map for your closest one here)
To use them with our professional mini regulator you need the adaptor available above.
To use with the 19L keg it is best to use the steel disconnect so that it hangs vertically and for the same reason the plastic disconnect works better with the mini kegs (as you can see in the product pictures).
You can also combine them with a gas manifold for gassing multiple kegs at once for either carbonating or dispensing.